The Bilstein B8 2009 BMW Z4 sDrive30i Rear Shock Absorber is a high-performance suspension product designed to provide superior handling and stability for the BMW Z4 sDrive30i. This shock absorber is constructed using a monotube design that features a gas-pressure construction and a self-adjusting deflective disc valve. It is also equipped with a digressive piston that provides a more comfortable ride by reducing the harshness of road irregularities. The shock absorber is built with a zinc-plated finish for superior corrosion resistance and long-term durability.