[Waterproof ABS Material] The RFID key fob is made of high-quality ABS material, the shell is strong and durable, has good waterproof, shockproof, and anti-corrosion performance, allowing you to use it better in your environment. After multiple processes, product quality can be well guaranteed. The red and blue colors provide you with more choices. [Comes with a Portable Keychain] Each fob is equipped with a keychain, which can be hung on keys and other items for easy use and to avoid loss. The volume of the key fob is 3.3x2.9x0.6 cm, which is small in size and convenient to carry. It can be put into pockets and backpacks. Its compact format makes it better for daily use. [TK4100 Chip] The type of RFID sensor ID card chip is TK4100, working frequency: 125Khz, you can choose the appropriate access card according to your needs. Compatible with standard ID access devices or ID systems. Each chip has its own ID, which is stored in the chip and on the back of the label for security. [Read-Only & Easy to Read] Cannot be programmed! It does not support and is not compatible with UHF and encrypted systems, such as HID, Radio, Cobra, Keri, APCiK, Indala, Isonas, Nexus, etc. The waterproof RFID key fob is suitable for 125KHZ card readers, and the reading distance is 0-10 cm. [Good Helper for Access Control System] RFID key fob can be used in a variety of environments, suitable for access control, hotel locks, employee attendance, campus visits, identity recognition, security systems, parking lot access, attendance registration, etc. It can be used in any situation where an access control system is needed, such as offices, homes, schools, communities, etc. Support: Read-only, not writable. Working Frequency: 125KHZ Size: 29x33x6mm Material: ABS Color: Blue, Red Package Contents: 50 pcs Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowed measurement error is +/- 1-3 cm.