If you are trying to fit a COMAND 2.0 with part number A210 820 xx xx or A208 820 xx xx into a W163 ML or a car without CANbus, then you need this device which take's the car's ignition, lights and speed signals and makes the CANbus needed for the A210/A208 COMAND units.

It also includes the adapter leads to connect to the car's C connector and power the CD changer and wakeup signals for phone / BOSE sound system etc.