ETEKJOY10 PCS Writable 125kHz RFID Sticker Coin Adhesive Back T5577 Proximity ID Card Token Key Tag Rewritable Dia 25mm

I purchased these because I got tired of carrying around my key fob. I was trying to minimize my EDC. I figured I always carry my phone so it would be great if I could dump the fob for something I could stick in my phone case. The maintenance guy at my building claimed they could only do the HID brand fobs. So using some equipment my friend had I copied my fob and wrote it to this coin. It worked perfectly. No more fob! My only gripe is these are a tad thick. They won't work in most phone cases. I did manage to get it to work with one of my 3 cases. The adhesive is strong but not strong enough to just stick to the outside of something like a phone that's always in use.

Works perfectly for one access card. (older access system).Our other access card seems to have a more sophisticated technology.The writeable stickers do not work for that system.

The adhesive is as strong as you can reasonably expect, it's no epoxy, but a long as you're treating it like a sticker, and not super glue, you're fine. It has more detection range than the card I copied. And yes, it DOES work just fine with flipper zero. Flipper zero can write to it without any problems, with or without the polymer case. They come blank, so if you don't have access to some sort of rfid writer, like a flipper zero, these won't be of much use to you.

Was able to write badge IDs to these, still works well after a few months. Adhesive works great.

These are not rewritable, they don't work.