CTSMC004.2 Mercedes Quadlock Audio 20 Steering Control Interface. This new range of two part Steering Control adaptors from Connects2 allows you to replace your radio and maintain your steering controls. Also provides CANBUS interfaces such as reverse signal, speedpulse and ignition and connects to Telephone button. You will also need relevant patch lead for you chosen head unit such as CTPIONEERLEAD for Pioneer. See Additional Information for Vehicle Applications.