The Bilstein B4 2009 BMW 535i Base Wagon Rear Shock Absorber is a high-performance shock absorber designed to improve the ride and handling of your vehicle. It features a monotube design with a gas-pressure construction, which provides superior performance and durability. It also includes a self-adjusting deflective disc valving, which allows for improved dampening control and a smoother ride. This shock absorber is designed to fit the rear of the 2009 BMW 535i Base Wagon and is a direct replacement for the original equipment.