Custom Retention Boxes
Custom retention boxes that hold a product in a stretched film membrane over a corrugated frame, so it floats clear of every wall of the shipping box, from 100 units. No foam, no fill, nothing to size to the product except the frame — the packaging that replaced peanuts for anything fragile and oddly shaped.
The product floats in a film, and nothing touches the box
- Frame
- E, B or C flute corrugated, die-cut, folds at the bench
- Film
- PU or PE membrane, 2–4 mil, glued to the frame; low-tack option
- Styles
- Retention (one frame), suspension (two frames), folded-frame retention
Get a price for Retention Boxes
Send the size and quantity — we reply the same working day with a price, a dieline and a date. Artwork optional at this stage.
- Free dielineThe flat drawing comes with the quote, before you commit.
- Proof before pressNothing is printed until you have seen it laid on the dieline.
- Die kept for reordersTooling is paid once. Every reorder skips straight to press.
- Quoted in four marketsUS, UK, Canada and Australia, in the delivery currency.
Retention, suspension, and the difference
Retention holds the product against one frame with the film over it; the frame sits in the base of the box and the product is pinned to it, clear of the walls. Suspension uses two frames, one above and one below, with the product held between two films in the center of the box, clear of the floor and the lid as well. Retention is cheaper and handles most products; suspension is for glass, instruments and anything that must not touch anything.
| Retention, single frame | Product pinned to one frame; phones, tools, hard goods |
|---|---|
| Suspension, two frames | Product held between two films; glass, optics, instruments |
| Retention with a folded frame | Frame folds around the product on two axes; awkward shapes |
Why it replaced foam and peanuts
What it does not suit is a very heavy product — above about 30 lb the film cannot hold it — or a product with a sharp edge that would cut the film. For those, the corrugated insert on our mailer boxes with a die-cut corrugated insert page is the right tool.
- One pack fits a range of products — the film stretches over whatever is put on it — so a company shipping fifty SKUs stocks one retention size, not fifty foam sets.
- It ships flat and takes up a fraction of the space of foam or loose fill.
- The corrugated frame recycles with the box; the film is a small PE or PU sheet that peels off.
- There is nothing to clean up on the receiving end — no peanuts, no dust, no shreds.
Sizing the frame and the box
The frame is sized to the product's footprint plus a margin of an inch or so on each side for the film to stretch over; the box is sized to the frame plus the clearance the product needs above it — the product's height plus an inch. For a suspension pack, both frames are the same and the box depth is the product height plus two inches. The box is an ordinary RSC or a mailer, and the frame drops in. We size both from the product and check the outside against carrier bands, the way we describe in our note on box size and dimensional weight.
The film is glued to the frame, not heat-sealed, and it holds through months of storage. Frames are shipped flat with the film on and fold up at the bench.
The film
The membrane is a polyurethane or a polyethylene film, 2–4 mil, with enough elasticity to stretch over a product and enough tear strength to hold it through a drop. It is clear, so the product is seen through it, and it leaves no residue. For a product with a delicate finish, a lower-tack film is used; for a heavy one, a heavier gauge. The film is the one part of the pack that is not paper, and it is small enough that the whole pack is usually accepted as corrugated for recycling once the film is peeled.
Retention Boxes — specification
The rows that are specific to this build first, then what applies to every job we run. Anything not listed is a question, not a limit — send the brief.
This build
- Frame
- E, B or C flute corrugated, die-cut, folds at the bench
- Film
- PU or PE membrane, 2–4 mil, glued to the frame; low-tack option
- Styles
- Retention (one frame), suspension (two frames), folded-frame retention
- Load
- Up to about 30 lb; sharp edges excluded
- Box
- RSC or mailer sized to the frame plus product clearance
- Minimum
- 100 packs
On every job
- Print process
- Flexo in one to four colors straight onto the liner; litho-lamination where the box needs full color or a photograph.
- Color
- Flat colors on kraft. Full color needs a white top liner or a laminated sheet, because brown shifts every color warm.
- Tolerance
- Cutting plus or minus 1.5 mm. The flute compresses, so corrugated runs wider than folding board.
- Tooling
- No die on a regular slotted box, which is cut on a slotter. Die-cut mailers and trays need one, made once and kept.
- Food contact
- Food-grade liners and a vented build where the box carries hot food.
- Sustainability
- High recycled content through liners and flute as standard, and the box recycles whole if it is sealed with paper tape.
- Artwork
- Vector PDF or AI, 3 mm bleed, 4 mm safe area, fonts outlined. We check every file and send a proof before press.
- Dieline
- Supplied free with the quote, before you commit. Yours whether or not you order.
- Sample
- A plain unprinted sample at the finished size on request, for fit and construction.
- Reorders
- Skip the tooling and go straight to press at a lower unit price.
- Lead time
- Quoted with the price against your fill date rather than promised before we have seen the spec.
- Markets
- United States, United Kingdom, Canada, Australia — priced in the delivery currency, freight included.
Boards and films we build retention boxes on
Corrugated is a fluted sheet glued between two liners, and the flute decides nearly everything: how it prints, how it dents, how high it stacks. These are the grades we run.
E flute
About 1.5 mm. Prints well and folds crisply; dents under a stack. Retail boxes, mailers and light shippers.
1.5 mm, single wallB flute
About 3 mm. The working default for parcels — takes print reasonably and stacks reasonably. Most shipping boxes are B.
3 mm, single wallC flute
About 4 mm. More cushioning than B, slightly less stacking strength per weight. Common on grocery and produce cases.
4 mm, single wallBC double wall
B and C glued together, about 7 mm. Heavy or fragile goods, pallet stacking, anything over roughly 15 kg.
7 mm, double wallKraft liner
Brown, strong, absorbent. One or two flat colors flexo print well on it; photographs drink into the brown and go muddy.
Outer and inner linerWhite top liner
A bleached outer liner for full-color print on corrugated. Costs more and marks more easily than kraft.
Outer liner onlyRecycled-content corrugated
High post-consumer fiber through liners and flute. The default for shippers; a slightly greyer brown and no loss of strength at grade.
All flutesCoated and water-resistant
A coating or a wax-free barrier liner for damp stores and cold chains. Check the recycling stream before printing a claim on it.
B and C fluteNot sure which? Say what goes in it and where it is sold — the material follows from that. Our notes on recycled, recyclable and compostable cover which claims each stock can honestly carry.
- 01
Send what you have
A dimension, a photograph beside a ruler, or the product itself. No technical drawing needed — that part is ours.
- 02
We quote and draw
A price, a dieline and a date come back together. If a different build would suit the product better, that is in the reply too.
- 03
Approve the dieline
The flat drawing is yours to check: which panel is the front, where the folds fall, how deep the cavity really is.
- 04
Artwork on the dieline
You place your design on the flat we sent, or we place it for you, and you see a proof before anything goes to press.
- 05
A sample if you want one
A plain unprinted sample at the finished size shows fit and construction — the things a drawing cannot.
- 06
Cut, printed, shipped
The die is cut once and kept, so every reorder skips the tooling and goes straight to press at a lower unit price.
Format
Vector PDF or AI where possible. Raster artwork at 300dpi at final size, in CMYK.
Bleed
3 mm past every trim line, so a fraction of drift on the cutter never leaves a white edge.
Safe area
Keep type and anything important 4 mm inside the cut and away from every fold.
Color
Convert to CMYK before sending. Uncoated stock prints lighter; a spot color is the only exact match.
Fonts
Outline them or supply the files. A missing font substitutes silently and the proof will not match.
Barcodes
On a light, matte, unvarnished patch with the quiet zone clear — a code on gloss fails the scanner.
Not set up that way? Send it anyway — fixing a file is a short conversation, and we check every one before press. Our guide to preparing print files covers each point.
Corrugated takes fewer finishes than folding board, and the ones it takes it takes well.
Flexo on kraft
One or two flat colors straight onto brown. Cheap, fast, honest.
Litho-lamination
An offset sheet glued to the flute: full color and photographs on a shipper.
Aqueous varnish
Scuff resistance with no film, so the box still recycles whole.
White top print
Full color flexo on a bleached liner; brighter, and it marks more easily.
Inside print
A second pass on the inner liner — the panel a customer sees first.
Printed tape seal
The brand applied at the last moment, on paper tape that recycles with the box.
Not sure which suits the shelf it sells from? Say where the product is sold and we suggest one — our notes on specialty finishes show them on real boxes.
Sizing a corrugated box against the carrier, not the catalog: retention boxes
Corrugated is cut to your internal size, so the box goes round the product rather than the product going into a stock size. That is where the money is: a box 20 mm smaller each way is often a whole postage band cheaper.
- Internal dimensions
- Length, width and depth of the space you need. Board thickness is added outside that, and the flute is thicker than people expect.
- Clearance and void fill
- 5–10 mm a side for a rigid product. Size it properly and you need no void fill at all, which is cheaper and better received.
- Stacking
- Tell us how high the boxes stack on a pallet or a shelf. Edge crush grade is specified from that, not guessed.
- Weight
- The contents weight sets the flute and the liner grade. Over about 15 kg we move to double wall.
- Score allowance
- Corrugated needs more room at the folds than boxboard. The dieline accounts for it; a box drawn from flat dimensions comes out tight.
- Cutting tolerance
- Plus or minus 1.5 mm on corrugated, wider than folding board because the flute compresses.
Not sure your numbers are right? Send the product dimensions rather than the box dimensions and we work the box out — the full method is in our guide to measuring for a box.
Interactive · five steps · no sign-up
Build your Retention Boxes in 3D
Pick a shape, type a size, choose a board and a finish. The preview on the left redraws as you go, and the spec lands with us exactly as you set it.
Frequently asked questions
Got a question about retention boxes? The answers below cover what we get asked most. If yours is not here, send it with a brief, message us on WhatsApp, or call +1 503-461-4788 — we reply the same working day.
How does a retention pack work?
A film is glued across a corrugated frame; the product sits on the film, the frame edges fold down, and the film stretches over the product and pins it in place, clear of the box walls.
Retention or suspension?
Retention holds the product to one frame in the base; suspension holds it between two frames in the middle of the box. Suspension is for glass, optics and instruments.
Can one pack fit different products?
Yes — the film stretches over whatever is put on it, within the frame size. One pack usually covers a range of SKUs.
How heavy can the product be?
Up to about 30 lb. Above that the film cannot hold it and a corrugated insert is the right tool.
Does the film leave marks?
No residue. For a delicate finish we use a lower-tack film.
Is it recyclable?
The frame is corrugated and recycles with the box. The film peels off and is a small sheet of PE or PU.
Does it ship flat?
Yes, frames ship flat with the film on and fold up at the packing bench in a few seconds.
Does it replace foam?
For most products, yes. It replaced foam and peanuts for electronics, tools and small appliances because one pack fits many products and ships flat.
What box does it go in?
An ordinary RSC or a mailer sized to the frame plus the product height and an inch. We supply both, sized together.
What is the minimum order?
100 packs. The frame is die-cut and the film applied in-line; the die is reused on reorder.
How long does production take?
It depends on the frame size and the quantity. We give a date with the quote rather than a number before we have seen the product.
Will you send a sample?
A frame in your size with the film on, so you can pack your product, box it and drop it before the order.
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