Waterproof ABS Material: The RFID key tag is constructed from high-quality ABS material, featuring a strong and durable shell with excellent waterproof, shockproof, and anti-corrosion performance for reliable use. Multiple processes ensure product quality. Available in red and blue for 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 3.3x2.9x0.6cm, making it compact 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 create access cards as needed. Compatible with standard ID access devices or IDs. Each chip has a unique ID stored within and on the back of the tag for security. Read Only & Easy to Read: The chip is read-only and cannot be programmed. It does not support or is compatible with UHF and encrypted systems like HID, Radio, Cobra, Keri, APCiK, Indala, Isonas, etc. The waterproof RFID key fob is suitable for 125KHZ card readers with a read distance of 0-10 cm. Great Access Control System Aid: RFID key fobs are ideal for various applications, including access control, hotel locks, employee attendance, school visits, identity identification, security, parking access, and attendance tracking. They are perfect for any scenario requiring an access 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: 50 x 125Khz RFID Card Tags. Other products are not included. Note: Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowed measurement error is +/- 1-3 cm.