CUID Changeable M1 S50 Block 0 Changeable Writable UID Black Ring

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SKU: SF6047

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CUID Black Ring

The chip in this CUID ring varies from a standard UID chip.  It is a special Generation 2 type of UID chip.  It is used to duplicate Mifare Classic 1K access cards and keyfobs. Whilst generally it is best practice to use unique Mifare Classic 14443A tags for each user, there are some instances where you may wish to clone a card or fob and have multiple tags with the same UID and data. For example, access control with few users with no user having the ability to add new cards into the system. Or for access control that has a user limit which has been reached.

Special GEN2 CUID Ring:

  • All blocks (including Block 0) can be re-written multiple times 
  • Not easily detectable by a system with "anti-clone" feature  
  • IMPORTANT: Fob will die if an invalid Block 0 is written  
  • Use normal commands. eg. hf mf wrbl 0 B FFFFFFFFFFFF a473f601200804006263646566676869  
  • Answers to Chinese magic backdoor commands: NO 


  • Material: Zirconia Ceramic + Epoxy Resin
  • Thickness: 2mm
  • Chip: CUID
  • Frequency: 13.56
  • Colour: Black
  • Induction Distance: 2-5cm
  • Waterproof: Yes

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