Feature: 1. Practical Function: Read only, not writable. If you want to add these tags to your lock, please make sure your lock uses an unencrypted 125kHz frequency. 2. Reliable Performance: Innovative technology carefully crafted, fine workmanship, wear resistant and waterproof, drop proof and not easy to break. 3. Sensitive Induction: With intelligent chip, thickened copper wire, high sensitivity, high frequency, and has fast reading speed. 4. Convenient to Use: This door lock key fobs is compact, lightweight, easy to carry and store, portable and simple to use. 5. Wide Scope: Suitable for 125KHz proximity access control system and ID management system, suitable for community access control, checking attendance, parking lot. Specification: Item Type: Door Lock Key Fob Material: ABS Size: Approx. 25 x 35mm / 0.98 x 1.38in Frequency: 125KHz Erase: Read Only. Package List: 100 x Door Lock Key Fob