The Bilstein B12 2008 BMW Z4 Roadster 3.0si Front and Rear Suspension Kit is a complete suspension kit that provides superior performance and handling for your BMW Z4 Roadster 3.0si. This kit includes Bilstein's B12 Sport suspension system, which features monotube gas pressure shocks and struts that are designed to provide superior damping force and response. The kit also includes a set of progressive rate springs that are designed to improve ride comfort and handling. This kit is the perfect upgrade for any BMW Z4 Roadster 3.0si owner looking to improve the performance and handling of their car.