These black bubble stickers with our snazzy logo on the front are backed by a Type 2 NTAG213 chip. They are made of a hard epoxy, so they cannot bend and are slightly raised, like a button. The NTAG213 chip features 144 bytes of usable space and can be made read-only. They are fully compatible with NTAG203 stickers. Because these stickers contain no protective shielding, they will work best in conditions where they are not placed directly on metal. Compatible with all NFC-capable phones!