5/10/20/50/100/500 - 125Khz RFID Proximity ID Card Token Tags Key FobsFor the Re-Writable Range select 1."Colour - Blue" 2. "Amount - XYZ Re-writable Keyfobs" Operational Frequency: 125 KHz Dimension: 33mm (L) x 27mm (W) Colour: Blue, Black, Grey, Orange, Red and Yellow Chip type: EM4100, TK4100 Water-resistant Each comes with key ring Each tag has been pre-programmed with unique ID, which is Laser printing on it, please buy the re-writable keyfob is you would like to create your own ID Application uses: public transportation, parking, ID identification, attendance system, ticketing, card payment, product logo, etc. Please note, TK4100 read-only and cannot write.