Arnott's new, not remanufactured, air strut for the front left side of the 07-13 Mercedes-Benz W221 S-Class and W216 CL-Class, both with Airmatic and 4MATIC, AS-2853, features a custom-made and tuned twin-tube shock absorber designed to provide a responsive yet comfortable ride. The Arnott strut is built with a new ContiTech air bladder, bump stop, connector, air line fitting and heavy duty crimping rings. The Arnott design is not only more efficient, it's also much more affordable! Each air strut is backed by a Limited Lifetime Warranty. Arnott recommends replacing both O.E. front struts at the same time.