An extremely strong metal protective cap prevents access to the OBD port. Without your coded key, the OBD protector is impossible to be removed without damaging the plug and the wiring harness. No OBD access, means no electronic bypass of the vehicle by the thief! The selection of the OBD Protector model depends on the type of plastic the vehicle’s OBD port is manufactured from. If the plastic is flexible, the “R” model is recommended. If the plastic is dense, the “F” model is recommended. Model “F” has a retainer element, facilitating the insertion of screws into a dense plastic OBD port. OBD-R fits most Acura/Honda, BMW/Mini, Fiat/Chrysler, Ford (check plastic density), Hyundai/KIA/Genesis, Infiniti/Nissan, Land Rover, Toyota/Lexus/Scion, Mazda, Mercedes-Benz/Smart, Mitsubishi, Subaru, Volvo