A graded slab is the one card format with no opening to bridge. The shell is welded shut at the factory, so there is nothing to close. A Serial Seal™ here is your own number, in your own artwork, on the outside of somebody else's holder. The prefix and the starting number are two fields you type on the builder, and the sequence runs from there — so the only real decisions left are which edge it goes on and how many you need.
What a slab actually is
All four major holders are two-piece shells ultrasonically welded around the full perimeter, at roughly the mid-plane of the thickness. Beckett adds a sealed inner sleeve inside the outer shell. There is no seam on the front or back face.
Outside dimensions are less settled than you would hope. We found no published exterior spec for PSA — their size table describes the interior card window, not the shell — so PSA gets a range. The figures below are what we measured on holders that came through the shop.
| Brand | Outside W x H | Thickness T | Per-face landing, (1.77 - T) / 2
|
|---|---|---|---|
| PSA | 3.20"-3.50" x 5.25"-5.40" (range; see above) | ~0.25" | 0.76" |
| BGS / Beckett | 3.20" x 5.125" | 0.375" | 0.6975" |
| CGC | 3.125" x 5.25" | ~0.20" | 0.785" |
| SGC | 3.392" x 5.460" | 0.3225" | 0.724" |
SGC has the largest footprint, BGS is the thickest, CGC the thinnest. CGC also offers thick-card holders at greater depths — measure the edge before you pick a placement.
Note the formula in that last column. A folded seal is 1.77" long, so it is tempting to assume 0.885" lands on each face. That is the zero-thickness upper bound and nothing more. The real figure is (1.77 - T) / 2, and on a BGS slab the naive number overstates your grip by more than 20%.
Where the Serial Seal™ goes
Use a FOLD, over the bottom edge of the slab.
Width across the edge: 0.75" of seal on a ~3.25" bottom edge is 23.1% of it. Face coverage: 0.76" down a face of roughly 5.25"-5.40" is about 14% of the slab's height. The fold crosses the perimeter weld, because on these holders every edge does.
Bottom rather than top because of the label. On all four brands the grade label, cert number and barcode sit at the top of the front face, and a top-edge fold lands 0.69"-0.79" straight down onto them. Cover the cert and the slab gets harder to sell to anyone not holding it. A bottom fold puts three quarters of an inch on blank plastic below the card window, and the same on the back.
A side edge works too: 0.75" across a 5.25" side edge is 14.3% of it, same per-face landing. Check the side you pick is clear of printed text on the front.
Use a SINGLE if you want no adhesive on the front face at all. A single lies flat on one face, so the number goes on the back and the display side stays untouched. You lose the edge crossing. What remains is the number and your record of it, which is the part that does the work.
There is no opening to bridge here and no per-brand variant to order — one seal size covers every slab in the table, which is why the whole spec fits on one line: 0.75" x 1.77", fold, bottom edge. That leaves the artwork, and the gallery on the builder is where that gets picked.
Step by step
- Measure the thickness. The table is a starting point; your calipers give you the real per-face landing.
- Mark your no-go zones on the front face: label, cert number, barcode, card window.
- Wipe the target area with a dry microfibre cloth. No alcohol or solvent — it hazes the shell over the card image.
- Test the first seal of a run on a low-value or empty slab. Leave it a day, pull it, and look at what it leaves behind.
- Register the seal along the bottom edge, about three quarters of an inch showing on the front. Lay that half down, wrap it under, burnish both sides. You get one placement — a crooked seal is a seal you have spent.
- Photograph it immediately: cert number and serial readable in the same frame, dated. Then the back.
- Write the serial down against the order, the cert number and the buyer. A spreadsheet row is enough.
- Ship it with the cert still scannable. If your seal covers the barcode, start again.
What this does and does not do
A seal can be lifted off a slab and a different one put on in its place. The welded shell does not help you — your seal sits on the outside, and the outside is where anyone else can work too. The stock is holographic vinyl on permanent adhesive and it grips hard polystyrene well. That decides how carefully you place it, not what it proves.
What you are buying is the number. You pick the prefix, we print the sequence, and no two seals in a run carry the same one. Its job on a slab is to tie one shell to one row in your records: cert number, order, buyer, ship date. Photograph the slab with the serial and cert readable together and you have something you can send someone later. Without the logged serial and that photo, the seal is not doing anything.
Some layouts print VOID IF DAMAGED. It is a notice, not a mechanism — the FAQ has the plain version. Your serial is your own numbering on the outside of a third-party holder: it says nothing about the grade, does not authenticate the card, and does not indicate whether the shell has been opened.
Never put adhesive on a card. On a slab the card is welded inside a shell and never touches the seal, which makes this the easiest format on the shelf — a one-touch magnetic holder needs far more thought about where the adhesive lands.
How many do you need
One seal per slab, and a slab only spends one. Nothing comes back to be resealed the way a mailer or a team bag does, so your count is the number of slabs that leave your hands.
60 Serial Seal™ minimum · From $30.00 · As low as $0.30 each in bulk.
Two numbers you already have. Take the slabs you shipped last month and multiply by twelve. Then add whatever is sitting at grading, because each of those comes back needing a serial the day it sells. Round up to the next twelve — seals print in packs of twelve, and 60 is the smallest order.
Run it and see where you land:
- Eight slabs a month is 96 a year, and the next rung up is 120 seals at $54.00 — 45c each.
- Twenty-five a month is 300 a year: $135.00, still 45c a seal.
- Fifty a month is 600 a year: $240.00, 40c a seal — and the rate keeps stepping down past that, to 36c at 1,200, 33c at 2,400 and 30c at 4,200, where it stays.
Sixty seals is $30.00 if you just want to try the placement on a few shells first. The volume rate applies by itself at checkout — one tier per order, nothing to type in. No setup, die, or design fees. Commercial license and copyright included.
Set that against what a slab already costs to move: grading fees, a rigid mailer, a tracked label. At the 600 rung the seal adds 40c per shell — still under half a dollar on a card you have already spent real money to encase. The 60-seal minimum works out at 50c each, which is what finding out costs. If those slabs go out alongside raw cards in rigid holders, count those separately — sealing a top loader covers that end of the shelf.
Common mistakes
- Folding over the top edge. It covers the label, the cert number or the barcode, and a cert that will not scan is a problem for the person on the other end of the sale.
- Assuming 0.885" per face. On a BGS slab you get 0.6975". In our own handling a fold with much under roughly 0.55"-0.58" of landing per face stops gripping reliably — a bench rule of thumb, not a measured spec, so test one on your own shells first.
- High-tack adhesive on a display face. Residue on the front of a slab is hard to get off without hazing the plastic over the card. Default to the lightest thing that holds.
- Sealing a slab you are about to resubmit or cross over. The shell gets destroyed in that process, and graders set and change their own submission rules — check their current instructions before you put anything on a holder going back to them.
- Sealing but not logging. A number nobody wrote down is a pattern on a piece of film.
Questions people ask
Does putting a Serial Seal™ on a slab affect the grade?
No. The grade is the grading company's, printed on their label inside their shell. The serial is yours, on the outside. Keep the seal off the label, cert number and barcode and the slab reads exactly as it did.
Can I seal a slab I plan to crack?
No point. The shell is destroyed when you crack it and the serial goes with it. Seal whatever holder the card lands in next and start a new row.
Which edge should I use on a BGS slab?
Bottom, same as the rest. BGS is the thickest of the four at 0.375", so a fold leaves 0.6975" on each face — above the roughly 0.55"-0.58" of landing per face we treat as our working floor. The label is still at the top, so the reason has not changed.
Should I seal the slab or the shipping package?
Different questions. The seal on the slab is a number tied to that card. The seal on the outer package is about the parcel as it left you — see sealing a shipping package for placement on a mailer or box, and the return fraud page for how sellers use the two together.
What you are buying is a numbered run of holographic vinyl folds, one per slab, in your sequence. Sixty is $30.00, 50c each; at 600 a seal is 40c for $240.00, and the rate keeps falling to a 30c floor at 4,200, which holds for every run above it, with anything past 10,008 quoted rather than posted. A slab spends exactly one seal and never asks for a second, so the run you order is the run that ships. Gallery artwork and your own logo come out as the same numbered fold — the builder is where the sequence starts.
Serial Seal is an independent printer. We are not affiliated with, endorsed by or sponsored by PSA, Beckett, CGC, SGC, Ultra Pro, BCW, eBay, Whatnot, TCGplayer or any card manufacturer. Brand names are used only to describe the products they make. Nothing here is legal advice.