UID Changeable MF Classic 1K or 4K (4 bytes or 7 bytes)

VERY IMPORTANT: UID / Block 0 can only be re-written using the ACR122U with the provided software.

• Not with the Proxmark3 or other devices.
• UID / Block 0 can be re-written multiple times only by using the ACR122U. Software download link is provided with the cards. 
• Choose from the Classic 1K S50, 4K S70 or Ultralight EV1 card. Also choose from the common 4 byte UID card or the newer 7 byte UID card. 
• You can choose to lock Block 0 with the ACR122U software which will permantly lock Block 0. 
• Card may die if an invalid Block 0 is written 
• Answers to chinese magic backdoor commands: NO.

Specifications

• Frequency: 13.56 MHz
• Protocol: ISO14443A
• Rewrite Times: 100,000 times
• Read Distance: 0 ~ 10 cm(depends on the R/W device)
• Material: PVC
• Dimensions: 85 * 54 * 0.9 mm