· Product Detail: 40mm x 30mm x 4mm, small size, 100 pcs Ultralight C Keyfobs, made of ABS material, waterproof, drop-proof, high temperature resistant, stable and durable function, long service life. Strictly follow the ISO14443A protocol, need to ensure that the card reader supports the protocol and Ultralight C extended instructions (such as 3DES certification).· Chip: mifare Ultralight C MF0ICU2 chip, working Frequency: 13.56 MHz, with 192-bytes usable memory. Anti-cloning support by unique 7-byte Serial Number for each device, the Serial Number cannot be changed or rewrited. 32-bit user programmable OTP area. Field programmable read-only locking function per pagefor first 512-bit【Note: The app like NFC Tools, NFC TagInfo can read the Serial Number of the ULC key fobs】· Compatible: Compatible with Newly upgraded SAFLOK, KABA, ONITY and SALTO Locks. NOT compatible with AMIIBO and 125kHz Readers. This mifare ULC keyfob MF0ICU2 can be used on most access control security systems. Some access control/door lock systems (e.g. SAFLOK, KABA) require a special key format and cannot directly reuse cards from other systems. 【Note: If you want to add the ULC keyfob to your lock system, please ensure that your system is the same frequency】· Authorized Entry: The managers enter the unique identification serial number of the key fob into the access control system database and associate it with specific personnel and regional permissions through specialized card reader devices and management software. In the company's access control system, the employee's key fob serial number and the employee can enter the office floor, specific rooms and other permissions bound. Requires authorization to use, can not directly copy the information· Lock Bytes Irreversibility: Lock0 and Lock1 of Page2 are used to lock the storage page as read-only and cannot be modified after locking. Lock bits are set by binary bits (e.g., 11110000 corresponds to locked pages 4-7), which should be carefully planned and then written to avoid misuse leading to permanent locking of data. If you encounter any quality problems or non-human damage that prevents you from using it, please contact us.