[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 portability. It can be easily stored in pockets or backpacks. The compact shape enhances usability for daily applications. [TK4100 Chip] The RFID sensor ID card uses the TK4100 chip, operating at a frequency of 125 kHz, compatible with standard ID access control devices. Each chip has a unique ID number permanently stored and printed on the back of the tag for security purposes. [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 Radio, Cobra, APCiK, Indala, Isonas, etc. 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] Suitable for use in access control systems, including hotel locks, employee attendance, school campus access, identity verification, parking lot entry, and more. Ideal for offices, homes, schools, residential communities, and other locations requiring secure access management. 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 display settings may cause slight color variations between the image and the actual item. Measurement allowance is +/- 1–3 cm.