Waterproof ABS Material: The RFID key fob is made of high-quality ABS material, with a strong and durable shell, offering good waterproof, shockproof, and anti-corrosion performance for reliable use. The red and blue color options provide more choices. Comes with a Portable Keychain: Each tag is equipped with a keychain for easy attachment to keys and other items, preventing loss. The key fob measures 3.3x2.9x0.6 cm, making it small and convenient to carry in pockets or backpacks. Its unique shape enhances daily usability. TK4100 Chip: Features a TK4100 RFID sensor ID card chip with a working frequency of 125Khz, allowing you to choose the appropriate access card for your needs. It's compatible with standard ID access devices or systems. Each chip has a unique ID stored within and on the back of the tag for security. Read-Only and Easy to Read: The chip is read-only and cannot be programmed. It does not support or is compatible with UHF and encrypted cards like HID, Radio, Cobra, APCiK, Indala, Isonas, etc. The waterproof RFID key fob is suitable for 125KHZ card readers with a read distance of 0-10 cm. Great Helper for Access Control Systems: The RFID key fob is versatile for various applications, including access control, hotel locks, employee attendance, school campus access, identity identification, security systems, parking access, and more. It's ideal for any scenario requiring an access control system, such as offices, homes, schools, and communities. Support: Read-only, not writable. Working Frequency: 125KHZ Size: 29x33x6mm Material: ABS Color: Blue, Red Package Contents: 100 x 125Khz RFID Card Tags