[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 for reliable daily use. After multiple manufacturing processes, product quality is well assured. Available in red and blue colors for added choice. [Comes with a Portable Key Ring] Each tag includes a key ring, allowing it to be easily attached 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, making it compact and portable. It can be conveniently stored in pockets or backpacks. Its ergonomic shape enhances everyday usability. [TK4100 Chip] The RFID sensor ID card uses the TK4100 chip with a working frequency of 125 kHz, compatible with standard ID access devices or ID readers. 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 and is not compatible with UHF readers or encrypted readers such as Kaba, Radio, Cobra, HID, APCiK, Indala, Isonas, Paradox, 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] This RFID key fob is suitable for various applications including access control, hotel door locks, employee attendance, school campus visits, identity recognition, security systems, parking lot access, and attendance tracking. It can be used in any location requiring an access control system, such as offices, homes, schools, and 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 variations in color between the image and the actual item. Measurement error allowed is +/- 1–3 cm.