Note: These are 13.56MHz key fobs (tags). Keychain ID/IC card for access control systems. All key fobs come attached to key ring. If you want to register them to your lock system, please ensure that your system uses the same frequency 13.56MHz. Incompatible with other frequencies like 125kHz. Writable & Rewritable: With a high-quality ABS housing. It can be erased and written 10,000 times. Suitable for making new and back-up tags. Suitable for 13.56MHz RFID proximity access control system and ID management system. For example, register them to your RFID door lock as new keys if applicable. Approx. Fob Size: 1.58*1.26*0.18 inch. High-Quality Copper Coil inside. Casing Material: ABS Plastic. Color: Blue.Products from Botao's store Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-Dadangjia