WRITABLE & REWRITABLE: This tag features a rewritable chip and supports writing in 125kHz ID format and HID WG 125kHz format. Suitable for creating and backing up tags. FREQUENCY: 125kHz; Sensing Distance: 2.5 to 10 cm (1 to 4 inches); Data Storage Life: 10 Years. CHIPS: T5577 chips. These tags do not have pre-programmed ID numbers and must be programmed before use. Ensure you have a compatible 125kHz RFID writer before purchasing. MATERIAL: High-quality copper coil inside. Casing made of ABS plastic. Waterproof and durable. Package includes 50 pieces. NOTE: These tags cannot be used directly with RFID locks. Data must be written using a 125kHz RFID card writer or copier. Tags are blank and contain no data when shipped. Compatible with 125kHz RFID writers. Not compatible with ONITY systems or Proxmark3 RDV4. Chip: ATMEL T5577 Working Mode: Read-write capable compatible with 125kHz RFID card copiers/duplicators Storage Capacity: 330 bits (264 free bits available) Reading Distance: 0 - 10 cm Note: Must be programmed before use. This is a blank chip. Color: Black Material: Plastic Package Contents: 50 x Key Fob Only the above package content is included; other items are not part of this package. Note: Lighting effects and display settings may cause slight color variations between the image and the actual item. Measurement error allowance: +/- 1-3 cm.