[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. Produced through multiple manufacturing processes to ensure consistent quality. Available in red and blue colors for added choice. [Comes with a Portable Key Ring] Each tag includes a key ring for easy attachment to keys or other items, helping 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 teardrop design enhances everyday usability. [TK4100 Chip] Features a TK4100 RFID sensor ID chip operating at 125 kHz, compatible with standard EM ID access devices or ID readers. Each chip has a unique ID number permanently stored and printed on the back of the tag for security. [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 readers such as Kaba, Radio, Cobra, HID, APCiK, Indala, Isonas, Honeywell, Paradox, etc. Designed for use with 125 kHz card readers with a reading distance of 0–10 cm. [Good Helper for Access Control System] 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. 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