Welcome to our store! 1. 3.56MHz UID chip that can be changed, supports ISO14443A protocol. 2. Block 0 of the card is writable, you can write your own UID into it. 3. You can also use it to copy the UID of mf s50 cards. 4. Made of high-quality PVC material for light weight and maximum durability. 5. Stable and secure data transmission, very easy and convenient to use. Features: 13.56MHz UID chip that can be changed, supports ISO14443A protocol. Block 0 of the card is writable, you can write your own UID into it. You can also use it to copy the UID of mf s50 cards. Made of high-quality PVC material for light weight and maximum durability. Stable and secure data transmission, very easy and convenient to use. Specifications: Material: PVC Color: White Chip: 13.56MHz UID chip that can be changed Protocol: ISO14443A Thickness: 0.86mm Size: Approx. 85.5 * 54 mm / 3.4 * 2.1 inches Package List: 10 * IC UID Cards If you receive your item and find any product problems, such as damage or incorrect quantity, please contact us immediately. We will do our best to provide you with satisfactory customer service.