The Bilstein B4 OE Replacement 04-06 BMW X3 3.0i L6 3.0L Front Left Twintube Strut Assembly is a high-quality aftermarket strut assembly designed to provide superior ride comfort and handling performance. This strut assembly is constructed with a monotube design, which allows it to operate more efficiently than traditional twin-tube designs. The assembly is designed to provide improved damping performance, better handling, and a smoother ride. The assembly is also corrosion-resistant and comes with a limited lifetime warranty.