[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, allowing for reliable use in various environments. After multiple manufacturing processes, product quality is ensured. Available in red and blue colors for added choice.[Comes with a Portable Key Ring] Each tag includes a key ring, making it easy to attach to keys and other items for convenient use and to prevent loss. The key tag measures 3.3 x 2.9 x 0.6 cm, small and lightweight for easy carrying in pockets or backpacks. Its compact shape enhances daily usability.[TK4100 Chip] Features a TK4100 RFID sensor ID chip with a working frequency of 125 kHz, compatible with standard ID access control systems. Each chip has a unique ID number stored internally and printed on the back for identification. Suitable for use with 125 kHz readers.[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. Compatible only with 125 kHz ID card readers, with a reading distance of 0–10 cm.[Good Helper for Access Control System] This RFID key tag is suitable for various access control applications including door locks, employee attendance, school campus access, hotel locks, parking access, and identity verification. Ideal for use in offices, homes, schools, residential communities, and other secured areas.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 Key Tags Note: Light and screen display settings may cause slight color variations from the actual product. Measurement allowance is +/- 1–3 cm.