The Bilstein B16 2009 BMW Z4 sDrive30i Front and Rear Performance Suspension System is designed to improve the ride and handling of your BMW Z4. It features a monotube gas pressure construction that provides consistent damping performance. The system also includes 2 adjustable front struts and 2 adjustable rear shocks that allow for fine tuning of the ride and handling characteristics. The system is designed to provide superior performance and stability while also offering improved comfort and control. The system is also designed to be corrosion resistant and is backed by a limited lifetime warranty.