RFID Card Key 125 kHz compatible with the CFR-2204 RFID 12V Ignition Switch Engine Start Push Button System. Designed for American muscle cars Designed Mustang,/Camaro/ and Challenger style this replacement key card enables secure, RFID key card for engine start functionality across all CFR-2204 system. Keep a spare on hand for convenient access to your vehicle's push engine start button ignition RFID technology.