[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, the product quality is well assured. Available in red and blue to suit different preferences. [Comes with a Portable Key Ring] Each tag includes a key ring for easy attachment to keys and other items, helping prevent loss. The key tag measures 3.3 x 2.9 x 0.6 cm, compact and lightweight for convenient carrying in pockets or backpacks. Its ergonomic design enhances everyday usability. [TK4100 Chip] Features a TK4100 RFID sensor chip operating at 125 kHz. Compatible with standard ID access control devices and readers. Each chip has a unique ID number stored internally 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 readers such as Kaba, Radio, Cobra, HID, APCiK, Indala, Isonas, Paradox, etc. Designed for use with 125 kHz card readers, with an effective reading distance of 0–10 cm. [Good Helper for Access Control System] Suitable for various applications including access control, hotel door locks, employee attendance, school campus access, identity verification, security systems, parking access, and timekeeping systems. Ideal for use in offices, homes, schools, residential communities, and other locations requiring secure access. 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 Note: The actual item color may vary slightly due to lighting and display differences. Measurement error allowance: ±1–3 cm.