[Waterproof ABS Material] The RFID key tag is made of high-quality ABS material. The shell is strong and durable, with good waterproof, shockproof, and anti-corrosion performance, allowing for reliable use in various environments. After multiple manufacturing processes, product quality is well 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 or 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 carried in pockets or backpacks. The compact shape enhances daily usability. [TK4100 Chip] The RFID sensor ID card features a TK4100 chip with a working frequency of 125 kHz. Compatible with standard ID access control devices. Each chip has a unique ID number stored within 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 HID, UHF, or encrypted systems such as Radio, Cobra, HID, APCiK, Indala, Isonas, or similar. This waterproof RFID key tag works with 125 kHz card readers, with an effective reading distance of 0–10 cm. [Good Helper for Access Control System] This RFID key fob is suitable for various applications including access control systems, hotel door locks, employee attendance tracking, school campus access, identity verification, security systems, parking access, and timekeeping systems. Ideal for use in offices, homes, schools, residential communities, and other secured areas requiring 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 Card Tags Note: Light and display settings may cause slight color variations between the image and the actual item. Measurement allows for an error of +/- 1–3 cm.