Package contents: 20 NTAG203 NFC Tags + 1 FREE NTAG203 NFC keychain + 2 sheets of 12 vinyl stickersNFC Chip Specifications:NFC Chip Type: NTAG203Memory Size: 144 bytesRewrite Endurance: 100,000 cyclesLockable: yes (can be made read only)Data Retention: 10 yearsOperating Frequency: 13.56 MHzOperating Range < 2cm (depends on device)Compatibility:  compatible with NFC enabled smartphones (read FAQ for more info)Works with the new Nexus 4 phone and Nexus 10 Tablet and ALL other NFC capable devicesNFC Tag:Material: Rigid White PVC (approx thickness of a credit card)Dimensions: 30mm x 30mm (about the size of a quarter)Waterproof, Adhesive backingKeychain:Material: Rigid dark gray plasticDimensions:  36mm x 6mm