Custom Reinforced Mailer Boxes: Smart Packaging Guide

I still remember standing beside a converting line in a Corrugated Box Manufacturers facility outside Chicago, watching a run of custom reinforced mailer boxes come off the folder-gluer, and one small change in board structure turned a batch that failed at the corner crush test into a carton that held up cleanly through parcel simulation. The outer size had not changed at all, which is exactly why so many buyers miss the real story: custom reinforced mailer boxes are less about making the box larger and far more about engineering the right structure so the load moves through the panel, score, and flap system instead of punching through one weak spot. I’ve always thought that part of packaging is a little unfair, honestly—two boxes can look nearly identical on a pallet, and one survives a rough week in transit while the other folds like a lawn chair after one bad drop.

At Custom Logo Things, I’ve seen brands use custom reinforced mailer boxes for everything from cosmetics kits and subscription sets to electronics accessories and apparel bundles, and the reason is always the same. They want a carton that arrives looking tidy, resists compression in transit, and still carries a branded presentation that feels intentional rather than generic. That dual job—protection plus presentation—gives custom reinforced mailer boxes real value, especially for teams that are tired of apologizing to customers for dented corners and crushed inserts, which usually turns into a support ticket, a replacement shipment, and another $8.40 in carrier cost before anyone has even had breakfast.

What Are Custom Reinforced Mailer Boxes, and Why Do They Matter?

Plainly put, custom reinforced mailer boxes are mailer-style cartons built with extra structural support. That reinforcement might come from heavier corrugated board, doubled side panels, inner inserts, reinforced tuck flaps, edge wraps, or a tighter die-line that keeps the contents locked in place. The goal is not cosmetic; it is mechanical. In a parcel network, a box can see conveyor drops, stack pressure, vibration in trailers, and hard corner impacts when it gets tossed into bins, and custom reinforced mailer boxes are designed to handle those stresses better than a lighter standard mailer. A well-specified build might use 32 ECT single-wall corrugated for light items, 44 ECT B-flute for moderate weight, or even 48 ECT double-wall for heavier kits, depending on how much abuse the route is expected to deliver.

The difference between a standard mailer and a reinforced mailer often shows up first in edge crush resistance and stacking strength. A standard E-flute mailer might be fine for a 1-pound apparel kit, but if that same package contains a glass bottle, a printed insert, and a magnetic closure component, I’d usually push the conversation toward custom reinforced mailer boxes with a stronger board spec or internal support. I’ve sat with clients who assumed the issue was the box failing, when in reality the product was moving inside the carton and making the corners take all the abuse. I remember one beauty brand in Los Angeles that swore the corrugated supplier had “bad board,” but the real villain was a serum bottle sliding just enough to turn every shipment into a tiny percussion test, and the fix was a 350gsm C1S artboard insert cut to hold the neck and base in place.

These boxes are common in ecommerce, subscription kits, promotional shipments, cosmetics, apparel, electronics accessories, and premium unboxing programs because they solve two problems at once. They protect the product, and they support branded packaging and package branding in a way that a plain brown shipper never can. For brands that care about retail packaging impressions even in a direct-to-consumer shipment, custom reinforced mailer boxes can be the sweet spot between a decorative carton and a freight-grade shipper, especially when the print spec includes a clean one-color exterior or full CMYK inside panel for a launch campaign.

“The strongest box I ever shipped wasn’t the thickest one on paper; it was the one with the right fit, the right scores, and no wasted space.” That’s something a plant manager told me during a run in Nashville, and he was right.

Honestly, I think that’s where a lot of people get tripped up. They compare cartons by board thickness alone, but custom reinforced mailer boxes are a system, not just a material. The flute profile, the panel design, the fit, the closure style, and the print layout all affect performance. If one piece is off, the carton can still fail even if the board itself looks impressive on a spec sheet. A beautifully printed box using 300gsm SBS with a weak score line may still lose to a plain kraft mailer in a 3-foot drop test, which is why the whole structure has to be considered together.

How Reinforced Mailer Boxes Work in Real Shipping Conditions

The structural logic behind custom reinforced mailer boxes is simple once you’ve watched enough cartons move down a line. Corrugated board works best when it spreads impact across multiple surfaces instead of concentrating stress at one point, and reinforcement helps the box do exactly that. Flute orientation matters here, because the corrugation is doing more than filling space; it is acting like a tiny arch system that helps resist compression. In practical terms, a well-designed mailer can absorb drops and stack loads far better than a weak carton of similar size, particularly on routes that run from a plant in Atlanta to fulfillment centers in Dallas or Phoenix where dry air and trailer vibration can expose weak spots quickly.

One of the more common reinforcement methods is double-wall corrugated board, especially for heavier packs or long transit lanes. I’ve also seen very effective builds using glued sidewalls, reinforced tuck-in flaps, edge wraps, and inner pads that cradle a fragile item in a fixed position. For example, a skincare client I worked with in a packaging plant in Pennsylvania shifted from a single-wall mailer with loose paper fill to custom reinforced mailer boxes with a product-specific insert, and damage complaints dropped sharply because the jars stopped colliding with each other during handling. In that case, the board remained a 32 ECT kraft outer, but the insert was the real hero, and the entire pack-out cost only $0.12 more per unit at 5,000 pieces.

Another thing people underestimate is how these cartons behave under carrier stress. Parcel networks are rough on packaging. Boxes get dropped from conveyor transfer points, squeezed in sorted bins, and shoved sideways in trailers where vibration and lateral movement can gradually loosen weak closure points. If moisture enters the picture, especially on longer routes through humid regions like Georgia, Florida, or the Gulf Coast, board softness becomes part of the failure story. That is why custom reinforced mailer boxes often make sense for shipments that are not especially heavy but are still vulnerable to repeated touchpoints, because a carton that looks fine in the warehouse can start losing stiffness after two hours in a damp staging area.

When I visited a Bobst-equipped converting operation in Indiana, I watched the team tune scores by fractions of a millimeter so the folds would close cleanly without cracking the liner. That kind of score control sounds minor until you see a mailer pop open at the flap because the crease was too shallow or the fibers were overcompressed. Clean assembly matters, and with custom reinforced mailer boxes, the folder-gluer and die-cut tolerances matter just as much as the board grade. On one run, a 0.4 mm score adjustment was the difference between a snug tuck and a flap that kept springing open on the line.

The other big advantage is fit. A tighter internal fit reduces product movement, which means the box itself is not being asked to do all the work. In many cases, I’d rather use a slightly more precise dieline, a properly sized insert, and a moderate board spec than jump straight to the heaviest material available. That’s a smarter way to approach custom reinforced mailer boxes because the protection comes from the whole pack-out, not from raw thickness alone. It also keeps freight math under control, since shaving even 2 ounces from each parcel can change your DIM weight class and reduce the landed cost by $0.30 to $0.90 per shipment on common ecommerce lanes.

For brands that want a broader look at available carton formats, our Custom Packaging Products page is a good place to compare structures, and if your shipment is light but still needs a clean presentation, Custom Poly Mailers can be a useful alternative for certain apparel and accessory programs. A soft-goods shipment that weighs under 8 ounces does not always need a reinforced carton, while a fragrance bundle with a glass bottle and paperboard tray usually does.

Industry testing standards can help frame these decisions, too. For parcel performance, many teams look at ISTA procedures, and for recycled content or fiber sourcing discussions, FSC certification can matter a great deal. If you want a neutral starting point on transport testing, the International Safe Transit Association has useful resources at ista.org, and for paper fiber and forest stewardship, fsc.org is a solid reference. Those standards are often used alongside internal drop testing from 24 inches, 36 inches, or 48 inches depending on parcel weight and carrier profile.

Custom Reinforced Mailer Boxes: Key Factors That Affect Performance, Cost, and Print Quality

Material selection is the first decision that really shapes the outcome of custom reinforced mailer boxes. E-flute gives a smoother print surface and a slimmer profile, B-flute offers a bit more stacking strength, and double-wall options add another layer of protection when the product is heavier or the route is especially rough. Kraft liners are often preferred for a natural look and good durability, while recycled content can support sustainability goals if the board spec still meets the performance requirement. I’ve seen buyers insist on the thinnest board possible just to save pennies, then pay more later in damage claims and reshipments, which is exactly the wrong trade. If you’ve ever had to explain why a “cost-saving” carton became a very expensive carton, you know the special kind of headache I mean, especially after a $0.15 per unit for 5000 pieces quote turns into $0.62 once inserts, coatings, and a heavier board are added.

Sizing is equally important. The internal dimensions, not the outer ones, determine whether the product will shift, rattle, or sit snugly enough to stay stable. A well-fit box with a simple insert can outperform a larger carton with void fill every time. In the best custom reinforced mailer boxes I’ve helped develop, the product fit was measured to within a few millimeters, and the insert held the item so it could not move more than a small amount during a drop test. One electronics accessory brand in Seattle reduced returns after switching from a loose 9 x 6 x 3 inch mailer to a tighter 8.5 x 5.75 x 2.75 inch build with a 1.5 mm paperboard cradle.

Pricing depends on several levers at once. Board grade, structural complexity, print coverage, finishing, minimum order quantity, and tooling all affect unit cost. As a rough planning range, I’ve seen straightforward custom reinforced mailer boxes run around $0.35 to $0.65 per unit at 5,000 pieces for simple kraft builds, while more complex printed cartons with inserts, specialty coatings, or heavier board can move into the $0.75 to $1.40 range depending on dimensions and geography. A one-color logo on the outside is not the same cost profile as full-coverage CMYK inside and out, and a die-cut insert often changes labor and material usage more than the buyer expects. For a 5,000-piece run out of a facility in Dongguan or Ningbo, the same size carton can vary by more than 18% depending on whether the insert is folded corrugate or flat paperboard.

Print and branding choices should match the box’s actual job. Flexographic printing is efficient for simpler graphics and larger runs, while digital printing is often better for short runs, fast turnarounds, or variable artwork. CMYK graphics can make custom reinforced mailer boxes feel closer to premium product packaging or retail packaging, but large solid ink coverage near folds can sometimes create cracking or scuff visibility if the board flexes a lot. Matte coatings tend to hide handling marks better, while gloss can brighten colors but may show abrasion more readily. If the route is particularly rough, an aqueous coating with a 15–18 micron target can be the more practical finish than a high-gloss laminate that shows every scrape from the conveyor line.

Operational factors matter just as much as aesthetics. If your packaging is headed for a direct-to-consumer program, a strong but clean structure is usually enough. If it is going into a retail-ready display, then alignment, print registration, and shelf presentation matter more. I always tell clients that custom reinforced mailer boxes are not just shipping boxes with a logo; they are part of the buyer’s first physical impression, which is why custom printed boxes need both functional and visual discipline. A DTC subscription box shipped from a warehouse in New Jersey may need less visual complexity than a retail rollout in Toronto or London, but both still need crisp folds and reliable closure performance.

One practical note from a supplier negotiation in Shenzhen: the client wanted a very dark, flood-coated exterior on a low-cost kraft board, but the sample showed scuffing at every high-friction fold. We adjusted the print coverage, moved the heavy ink away from the scores, and kept the same general look with a much better result. That kind of detail is exactly why custom reinforced mailer boxes should be specified with someone who understands both press behavior and distribution behavior. In this case, the revised artwork stayed within a 70% ink coverage limit on the panels that flexed most, and that single change cut visible rub marks by roughly half.

How Do You Order Custom Reinforced Mailer Boxes?

Ordering custom reinforced mailer boxes starts with the product, not with the artwork, because the structure has to solve the real shipping risk before anything else gets approved. That means measuring the packed item carefully, defining how much movement is acceptable, and deciding whether the carton needs more board, a tighter fit, or an insert that keeps the contents from shifting. A reliable supplier will ask about weight, fragility, destination, pack-out sequence, and shipping method before quoting, and that early conversation usually saves more time than any revision later in the process.

Once the structure is defined, the next step is choosing the board grade, closure style, and print approach. For many custom reinforced mailer boxes, that means deciding between kraft or white liners, selecting a flute profile, and confirming whether you need one-color print, full CMYK, inside printing, or specialty finishing. It also helps to request a prototype before placing the full order, because a sample is often the quickest way to confirm whether the dieline, closure tabs, and insert geometry are truly doing the job. A box that looks right on screen can still fold badly in the plant if the score lines and tuck flaps were not aligned to the real material.

If your packaging program includes multiple SKUs, ask about footprint standardization. One master size with insert variations can often reduce tooling complexity and make replenishment easier. That is one reason many growing brands prefer custom reinforced mailer boxes over a different carton for every item, especially when the product family changes often but the shipping profile stays relatively consistent. The goal is not just to order a box; it is to build a repeatable system that scales cleanly as the brand grows.

Step-by-Step: How to Design and Order the Right Box

Start with the product, not the box. Measure length, width, height, weight, fragility, and the accessories that must ship together, such as chargers, sample cards, cables, or printed literature. If the product has sharp corners, liquid components, or surfaces that scratch easily, note that up front. The best custom reinforced mailer boxes start with a clear picture of what is actually being protected, because fragile can mean very different things for a glass dropper bottle, a folded garment set, or a cosmetic palette. If the item weighs 14 ounces packed with a 2-ounce insert, that changes the board choice far more than a rough guess ever will.

Next, choose the protective structure. A single-wall reinforced build may be enough for lightweight shipments, while a heavier or more sensitive product may call for double-wall construction, internal pads, or edge-strengthening features. Some programs need immobilization more than they need extra board, and that distinction saves money if you make it early. In my experience, custom reinforced mailer boxes perform best when the protection strategy is tied to the product’s real failure risk rather than a default assumption that thicker is always better. A 32 ECT E-flute carton can be enough for a 10-ounce candle set, but a 24-count sample assortment with glass vials usually needs a different answer entirely.

Then build the artwork and structural dieline together. That sounds obvious, but I’ve lost count of the times a brand finalized a beautiful layout only to discover the logo sat across a fold line or the closure tab covered a key graphic. With custom reinforced mailer boxes, the inside and outside are both part of the design system. Folds, scores, tuck tabs, and glue zones need to be planned so the box closes properly and the branding still looks intentional. A good prepress team in Guangzhou or Los Angeles will usually send a PDF proof, a structural line drawing, and a flat sample showing glue areas before any plate or digital setup is finalized.

Request samples or prototypes before committing to a full run. A sample should be tested the way the carrier network will treat it: drops from realistic heights, compression checks, vibration, and a pack-out trial with real product. If you are shipping through a major parcel network, a carton that feels solid in your hand can still fail in distribution if the scores are too tight or the product shifts two inches in transit. That is one reason I insist on test packs for custom reinforced mailer boxes whenever the contents are fragile, premium, or expensive to replace. A prototype usually costs $35 to $120 depending on complexity, which is far cheaper than replacing 500 damaged orders after launch.

Final production details should always be confirmed in writing: quantity, print method, carton style, board specification, insert count, pack format, and shipping timeline. If you are ordering from a packaging supplier, ask for the internal size, the outer size, and the board caliper in the same quote. I’ve seen confusion cost a week of rework because a customer assumed a small mailer meant one thing in their office and another thing on the factory floor. A clear quote should also list whether the board is 350gsm C1S artboard, 32 ECT corrugated, or a specific double-wall grade, because those details change both strength and price.

A practical order checklist for custom reinforced mailer boxes looks like this:

• Exact product dimensions, including any accessories
• Actual product weight and the heaviest packed configuration
• Board preference, such as E-flute, B-flute, or double-wall
• Print requirement, including one-color, CMYK, or inside printing
• Insert or partition needs, if any
• Quantity target and replenishment plan
• Delivery deadline and destination ZIP or port

Typical Production Timeline and What Happens at Each Stage

The workflow for custom reinforced mailer boxes usually starts with briefing and quotation, then moves into structural review, dieline creation, artwork approval, prepress, material sourcing, press setup, converting, packing, and outbound freight. Each stage has its own bottleneck, and if you understand where the work actually happens, you can save time and avoid expensive surprises. A simple build with standard board and a single-color print can move pretty quickly, while a highly customized carton with inserts, coatings, and multiple print passes will naturally take longer. On a well-run line in Suzhou or Chicago, the quote-to-prototype stage may take 2 to 4 business days, while the physical production stage can move much faster once the proof is locked.

For a straightforward production run, I usually plan on 12 to 15 business days from proof approval, assuming materials are available and no major structural changes are needed. If the job includes specialty finishes, multiple insert pieces, or unusual board sourcing, that can stretch to 18 to 25 business days, and freight timing sits on top of that. Custom reinforced mailer boxes are fast when the spec is clear, but they slow down the moment art changes keep arriving after the dieline has been approved. A client in Texas recently moved a launch back 4 business days simply because the inner print file came in with the wrong trim marks, and the prepress team had to rebuild the layout from scratch.

Delays often happen in the same places: late artwork revisions, unclear fit specifications, sample revisions, or board shortages. I once watched a six-day delay turn into a two-week delay because a client kept moving the logo by a quarter inch after prepress had already locked the form. Another common issue is sample approval taking longer than production, especially when two internal stakeholders each want a different version of the same box. With custom reinforced mailer boxes, decision speed is often as important as factory speed, and one round of approvals delayed by 48 hours can ripple through an entire ship date.

Factory scheduling adds another layer. Press availability affects print start dates, the folder-gluer schedule affects converting windows, and coatings or lamination can introduce drying or curing windows that must be respected before cartons are packed. Outbound freight planning matters too, especially if the shipment is crossing multiple states or moving overseas. Good suppliers will tell you exactly where the job sits in the queue, and that transparency is worth more than vague promises. If the order is urgent, ask your packaging partner whether they can simplify the print, hold the insert count steady, or standardize the carton footprint to get custom reinforced mailer boxes moving faster. On an export order from a factory in Vietnam to the West Coast, that kind of standardization can shave 2 to 3 days off internal handling before the freight even leaves port.

Clean input shortens everything. If you provide print-ready art, accurate measurements, a clear unpacking sequence, and fast proof approval, you cut out most of the avoidable back-and-forth. That is usually the difference between a smooth run and a stressful one. In practical terms, a ready-to-go brief can keep a project within a 12 to 15 business day window, while a vague brief can stretch the same order well past 20 days.

Common Mistakes to Avoid When Choosing Reinforced Mailers

The first mistake is overbuilding the carton. More board is not always better, especially if the product is light or already protected by an inner package. Too much material can increase cost, add weight, and create a box that is harder to assemble without delivering meaningful shipping benefits. I’ve seen brands choose a heavy structure for a 6-ounce item simply because they wanted extra safety, only to find the final parcel cost jumped enough to hurt margins. Good custom reinforced mailer boxes should be sized to the risk, not to anxiety, because a move from a 32 ECT single-wall to a 44 ECT double-wall structure can add $0.18 to $0.40 per unit without changing the actual damage rate if the product was never at structural risk.

The second mistake is judging the box by outer dimensions alone. Outer size tells you almost nothing about internal clearance, fold behavior, or product movement tolerance. If the internal space allows the product to slide even half an inch in multiple directions, the carton is still vulnerable. With custom reinforced mailer boxes, the fit is part of the protection strategy, and that means you need internal measurements plus a plan for how the product is restrained inside the shell. A 10 x 8 x 2 inch mailer can be either excellent or useless depending on whether the insert and walls actually immobilize the item.

Another common error is poor artwork placement. Large solids across high-stress folds can crack, and logos placed directly on score lines can distort when the box is assembled. Glue seams also need breathing room. A beautiful design can become a production headache if it ignores where the carton physically bends. The best custom reinforced mailer boxes I’ve seen always respect the fold map first and the graphic layout second. That usually means leaving at least 3 to 5 mm of safe space from the score and keeping the heaviest ink away from the panel edges.

Shipping conditions are often underestimated as well. A carton that travels 50 miles locally is not the same as a box that rides through multi-touch parcel handling, summer humidity, and long-distance trailer vibration. If your product is headed to dense urban routes or hot warehouse environments, you need to factor in how the board behaves after several hours of exposure. That’s why tests and sample runs matter; they reveal what the spec sheet can’t. A box that performs in a 68°F office can behave very differently after a day in a 95°F loading dock in Houston or Miami.

Skipping sample testing is probably the biggest mistake of all. A box that looks strong in a photo may not hold up once the product is packed, taped, labeled, and tossed through a carrier network. Custom reinforced mailer boxes should be validated with actual product, actual inserts, and actual handling conditions, because the real world is never as tidy as a design mockup. A 20-minute sample test can prevent a $2,000 replacement run, and that is a trade I will take every time.

Expert Tips for Better Protection, Branding, and Savings

My first tip is to design for the product’s actual failure mode. If the item is cracking at the corner, then edge reinforcement matters more than simply thicker board. If the issue is rattling and abrasion, then inserts or partitioning are probably more useful than extra caliper. That mindset keeps custom reinforced mailer boxes efficient, which is exactly what you want if you are ordering at scale and watching every cent of landed cost. A smart carton built around the actual break point usually costs less than a heavy carton that solves the wrong problem.

Second, use inserts when immobilization matters more than raw box strength. A well-cut paperboard insert, molded pulp tray, or corrugated divider can stabilize the product so the outer carton does not have to absorb every movement. I’ve seen this work especially well in beauty kits and electronics accessory packs, where the contents are small, precise, and visually sensitive. A smart insert turns custom reinforced mailer boxes into a much better shipping system than a heavier shell alone. In one case, switching from loose kraft paper to a three-slot insert reduced in-box movement by about 80% and cut damage claims from 3.1% to 0.7% over the first 8,000 units.

Third, balance branding with durability. Large ink floods and heavy coating can look rich, but they should not sit directly on the folds that take the most stress. Keep your logo in a strong visual zone, use contrast wisely, and leave the critical closure areas less cluttered. This is one of those places where package branding and function need to cooperate. A clean, restrained layout on custom reinforced mailer boxes often reads more premium than a busy design anyway, especially when the artwork is printed on a 1-color kraft exterior with a crisp interior accent panel.

Fourth, save money by standardizing carton footprints across multiple SKUs where possible. If three product families can share one base footprint with minor insert changes, you reduce tooling variation and simplify inventory. You also improve the odds of better pricing because the production team can run longer, more efficient batches. That approach works well for brands that need custom printed boxes but do not want a different box for every single item. A single master footprint can often reduce tooling and setup costs by 10% to 15% across a seasonal program.

Fifth, think about freight before you finalize the spec. A carton that is slightly smaller, but still protective, may lower dimensional weight enough to save meaningful money on every shipment. That’s a practical advantage of custom reinforced mailer boxes that gets overlooked because people focus on board cost and forget the downstream carrier bill. The carton is part of the shipping equation, not separate from it. On a 2,000-order monthly program, saving even $0.40 per shipment can add up to $9,600 a year, which is far more than the difference between two board grades.

Here’s the short version I give clients after a long spec review: gather product measurements, define the shipping risks, request a structural sample, compare board options, and prepare a print-ready brief before you talk to a supplier. That sequence saves time and often saves money too. If you want the box to feel polished and still survive transit, custom reinforced mailer boxes are usually a strong place to start. A good supplier will usually quote the first sample within 3 to 5 business days and then build production around the approved prototype.

One more honest opinion: do not let premium become code for unnecessary complexity. A simple, well-fit reinforced mailer with the right board and clean print often outperforms an overdesigned carton with fancy coatings but poor structure. In packaging, elegance usually comes from restraint, not excess. I’ve had people ask for four different finishes, metallic accents, and a magnetic closure on a shipper that was mostly carrying socks, and I had to bite my tongue a little because, frankly, the box did not need to dress for a gala. A 350gsm C1S artboard sleeve with a 32 ECT corrugated shell would have done the job for a fraction of the cost.

For brands comparing formats, I usually suggest reviewing the full assortment of Custom Packaging Products alongside any mailer options you are considering, because the right answer is often a structure you had not planned on at the start. And if your program uses light apparel, soft goods, or non-fragile promo items, Custom Poly Mailers may still solve the job more efficiently than a carton in some use cases, especially when the packed weight stays below 12 ounces and the shipper does not need rigid edge protection.

For environmental questions, it also helps to look at broader packaging guidance from the U.S. Environmental Protection Agency at epa.gov, especially if your brand is trying to reduce material use while keeping transit performance acceptable. I’ve found that the best sustainability decisions are usually the boring ones: right-size the box, avoid excess fill, and pick the lightest structure that still passes the shipping test. A carton designed this way from a facility in Ohio, Mexico, or Guangdong can often reduce board usage by 8% to 12% without sacrificing strength.

In the end, custom reinforced mailer boxes are not just stronger cartons. They are a way to align shipping protection, visual presentation, and operational efficiency in one format. When the board spec is right, the dieline is clean, and the print plan respects the structure, custom reinforced mailer boxes can protect the product, support the brand, and keep the shipping experience feeling thoughtful instead of improvised. That balance is what makes them such a reliable choice for ecommerce teams shipping from places like Chicago, Los Angeles, Shenzhen, or Toronto, where lead times, freight lanes, and presentation standards all matter at the same time.