Use the part number. Nearly all Mercedes parts have a 10 digit part number stamped or engraved on them (e.g. 1298203026). If we stock an item with the same part number as yours, then the part will fit your car.
If we don't have your number in stock, we may still have a superseded part which is also compatible with your car, so please ask the gurus and they will diagnose this for you. They will reply within 1 working day.