[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 guaranteed. Available in red and blue colors to suit your preference. [Comes with a Portable Key Ring] Each tag comes with 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 easy carrying in pockets or backpacks. Its compact shape enhances daily usability. [TK4100 Chip] The RFID sensor ID card chip is TK4100 type, operating at a frequency of 125 kHz. It is compatible with standard ID access control devices. Each chip has a unique ID number 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 HID and is not compatible with UHF or encrypted systems such as Radio, Cobra, HID, APCiK, Indala, Isonas. The 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 can be used in various settings including access control systems, hotel door locks, employee attendance tracking, school campus access, identity verification, security systems, parking lot entry, and time attendance systems. Suitable for offices, homes, schools, and residential communities. 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 differences may cause slight color variations between the image and the actual item. Measurement allows an error of +/- 1–3 cm.