WRITABLE & REWRITABLE: This tag features a rewritable chip that supports writing in 125kHz ID format and HID WG 125kHz format. Suitable for creating and backing up access tags. FREQUENCY: 125kHz; Reading Distance: 0 to 10 cm (0 to 4 inches); Data Storage Life: Up to 10 years. CHIP: T5577 chip. This chip is not pre-programmed with an ID number. You must write data to the tag before use. Ensure you have a compatible 125kHz RFID writer before purchase. MATERIAL: High-quality copper coil and ABS plastic casing. Waterproof design. PACKAGE INCLUDES: 50 x Key Fobs NOTE: These are blank RFID tags and cannot be used directly with RFID locks. Data must be written using a 125kHz RFID card writer or copier. Not compatible with ONITY systems or Proxmark3 RDV4 devices. WORKING MODE: Read-write capable, compatible with 125kHz RFID card copiers/duplicators. STORAGE CAPACITY: 330 bits (264 free bits available). COLOR: Black MATERIAL: Plastic PACKAGE CONTENTS: 50 x Key Fob (other items not included) NOTE: Lighting and display differences may cause slight color variation between the image and actual item. Measurement tolerance: +/- 1-3 cm.