• Arnott’s new conversion kit features Eibach monotube shock absorbers • Premium conversion kit includes CNC-machined aluminum seats and powder-coated steel coil springs • Arnott’s kit is engineered in the U.S. and pre-assembled for easy installation Arnott has introduced a new steel coil spring conversion kit for the 2007-2013 Mercedes-Benz S-Class (W221 Chassis) with AIRMATIC and ADS and without 4MATIC.