CRUX SWRBM-57CRUX (SWRBM 57) RADIO REPLACEMENT W SWC RETENTION FOR MERCEDES, BMW, PORSCHE & SMART VEHICLES The CRUX SWRBM 57 is a Multi CAN radio replacement interface for select Mercedes Benz, BMW, Porsche & Smart vehicles. It facilitates the integration of an aftermarket radio to retain factory features with CAN bus based vehicles. This enhanced interface is also pre programmed for retention of steering wheel controls. This kit includes BOTH Quadlock and ISO