[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. After multiple manufacturing processes, product quality is well guaranteed. Available in red and blue colors. [Comes with a Portable Key Ring] Each tag includes a key ring for easy attachment to keys or other items, helping prevent loss. Dimensions: 3.3 x 2.9 x 0.6 cm. Compact size allows convenient carrying in pockets or backpacks. Ergonomic design enhances daily usability. [TK4100 Chip] Features TK4100 RFID chip, operating frequency: 125 kHz. Compatible with standard 125 kHz ID access control readers. Each chip has a unique, pre-programmed ID stored both in the chip and printed on the label. [Read-Only & Easy to Read] The chip is factory-programmed and read-only — it cannot be rewritten or reprogrammed. Not compatible with UHF, MIFARE, or encrypted protocols such as HID Prox, Indala, or others. Designed exclusively for 125 kHz card readers, with reading distance of 0–10 cm. [Good Helper for Access Control Systems] Suitable for various access control applications including door entry systems, hotel locks, employee attendance tracking, school campus access, identity verification, security systems, and parking access. Ideal for use in 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 Key Tags Note: Color appearance may vary slightly due to lighting and screen settings. Measurement tolerance: ±1–3 mm.