The square is double-sided plastic. You pop it open and position the Opendime inside, close it up and it seals it between the plastic films in place.
Got them for my lightning coins which is where my logo comes from.
Discussion
Got a link to buy?? Not seen before
These are Opendime V4s by Coinkite which is run by #[3].
These along with a Yubikey 5C is what I designed my wallet to hold nostr:note165hh4f9th2fpzlpgwzftqzqg2hsr3chf7ru0nvvks2cc0vmxvl7sdkreag
You can get 10% off Coinkite products if you buy through #[4] app.
Use #[5] referral code when you sign up as he put me on to this: 05RCCH
Get that Bitcoin circular economy flowing!