The Bilstein 16-21 BMW X1 B4 OE Replacement Suspension Strut Assembly - Front Left is a direct replacement for the original equipment (OE) suspension strut assembly. This strut assembly features a monotube design with a gas-pressurized piston, which provides consistent damping performance and a smooth ride. It is designed to provide superior handling, stability, and control for your BMW X1. The strut is made from high-quality materials and is corrosion-resistant for long-lasting performance. This strut assembly includes a dust boot, mounting hardware, and a limited lifetime warranty.