[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 ensured. Available in red and blue colors for added choice. [Comes with a Portable Key Ring] Each tag comes with a key ring, allowing it to be easily attached to keys, bags, 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. It can be conveniently stored in pockets or backpacks. Its ergonomic shape enhances usability for daily applications. [TK4100 Chip] The RFID sensor ID card chip is TK4100, operating at a frequency of 125 kHz, compatible with standard ID access control systems. Each chip has a unique ID number permanently stored in the chip and printed on the back for identification 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 Mifare, Radio, Cobra, HID, APCiK, Indala, Isonas, etc. This waterproof RFID key tag is designed for use with 125 kHz card readers, with an effective reading distance of 0–10 cm. [Good Helper for Access Control System] This RFID key tag is suitable for various applications including access control systems, hotel door locks, employee attendance tracking, school campus access, visitor management, identity verification, parking access, and timekeeping systems. It can be used in any location requiring access control, such as offices, homes, schools, and residential communities. Specifications: 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 allows for an error of +/- 1–3 cm.