The Bilstein 17-21 BMW 530i B4 OE Replacement Shock Absorber is a direct replacement for the original equipment shock absorber on the BMW 530i. It is designed to provide improved ride comfort and stability while maintaining the factory-specified ride height. The monotube design provides superior damping ability and consistent performance, while the zinc-plated finish ensures corrosion resistance. The shock absorber is designed and tested to meet or exceed OE specifications and is backed by Bilstein's limited lifetime warranty.