The Bilstein B6 2009 BMW Z4 sDrive30i Rear Shock Absorber is a high-performance shock absorber designed to provide superior handling and improved stability. This shock absorber features a monotube design with a gas-pressure construction that is specifically tuned for each application to provide maximum performance and comfort. It is constructed from a high-quality steel and is designed to withstand extreme temperatures and road conditions. The shock absorber also features a self-adjusting deflective disc valving system that provides a consistent dampening response regardless of the terrain. This shock absorber is ideal for those looking for an upgrade in performance and handling.