The Bilstein B8 2003 BMW Z4 2.5i Front Left 36mm Monotube Strut Assembly is a high-performance suspension upgrade for the BMW Z4. It features a monotube design that provides superior handling and response, and a 36mm diameter for increased strength and stability. The strut assembly is designed to improve handling and reduce body roll, while providing a comfortable ride. It is a direct replacement for the stock struts, and comes with a limited lifetime warranty.