WRITABLE & REWRITABLE: This tag features a rewritable chip that supports writing in 125kHz ID format and HID Wiegand 125kHz format. Ideal for creating and backing up access tags. FREQUENCY: 125kHz; Sensing Distance: 2.5 to 10 cm (1 to 4 inches); Data Storage Life: Up to 10 years. CHIP: T5577 chip. It does not come with a pre-programmed ID number. The chip must be programmed before use. Ensure you have a compatible 125kHz RFID writer before purchase. MATERIAL: Built with high-quality copper coil and encased in durable ABS plastic. Waterproof and robust design. 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 preloaded data. Compatible with 125kHz RFID writers. Not compatible with ONITY systems or Proxmark3 RDV4 devices. WORKING MODE: Read-write capable, suitable for use with 125kHz RFID card copiers or duplicators. STORAGE CAPACITY: 330 bits (264 free bits available). READING DISTANCE: 0 to 10 cm. COLOR: Black MATERIAL: Plastic PACKAGE CONTENTS: 50 x Key Fob Note: The actual product color may vary slightly due to lighting and display differences. Measurement tolerance is +/- 1-3 cm. Only the items listed above are included.