These are packs of CD/Diskette envelopes. Yes, diskette! That's actually still printed on the packaging! No clue how old these might be, but I found them at a local independent dollar store for $1.39 per pack of 5, and they're made out of pretty sturdy chipboard, with a soft inner paper lining (basically the same stuff regular paper CD sleeves are made of), and I couldn't resist buying like 3 packs.
They measure 5in x 5.25in or 12.7cm x 13.3cm and I have verified they perfectly fit optical discs and 3.5in floppy discs (you can even easily fit an optical disc inside another paper sleeve for added protection if you're paranoid).
The "Place Stamp Here" square isn't superfluous - given you use a Non-Machinable Surcharge stamp, you can absolutely send one of these with just a single stamp! Though if I'm mailing discs, I prefer to get a tracking number.
Anyways if you want a Disc mailed to you just hmu
