[Waterproof ABS Material] The RFID key tag is made of high-quality ABS material, with a strong and durable shell that offers good waterproof, shockproof, and anti-corrosion performance, ensuring reliable use in various environments. After multiple manufacturing processes, product quality is well guaranteed. Available in red and blue colors for added choice. [Comes with a Portable Key Ring] Each tag includes a key ring, allowing it to be easily attached to keys or other items for convenient use and to prevent loss. The key tag measures 3.3 x 2.9 x 0.6 cm, making it compact and easy to carry in pockets or backpacks. Its ergonomic design enhances daily usability. [TK4100 Chip] The RFID sensor ID card uses the TK4100 chip with a working frequency of 125 kHz, compatible with standard ID access control devices. Each chip has a unique ID number permanently stored in the chip and printed on the back of the tag for identification. [Read Only & Easy to Read] The chip is read-only and cannot be rewritten or programmed. It does not support UHF or encrypted formats such as Mifare, HID, Indala, Isonas, or similar systems. This waterproof RFID key tag works with 125 kHz card readers with a reading distance of 0–10 cm. [Good Helper for Access Control System] This RFID key fob is suitable for various applications including access control, hotel door locks, employee attendance, school campus visits, identity verification, security systems, parking access, and more. Ideal for use in offices, homes, schools, residential communities, and other locations requiring secure access. Support: Read Only, Not Writable Working Frequency: 125 kHz Size: 29 x 33 x 6 mm Material: ABS Color: Blue, Red Package Contents: 50 x 125 kHz RFID Card Tags Note: Light and screen display settings may cause slight color differences between the image and the actual item. Measurement allows an error of +/- 1–3 cm.