Suncore's 128M-20-2 Air Compressor Pump is a brand new air suspension compressor designed for the W251 chassis R Class Mercedes-Benz. This compressor works for models equipped with only the rear air leveling suspension, and includes the necessary OE electrical connectors and comes ready to be installed on your vehicle. Be sure to check the bellows and air lines in your rear air suspension before replacing your worn air compressor pump, as the pumps usually fail because they continuously try to fill a leaking air spring or strut.