The Bilstein 17-21 BMW 530i B4 OE Replacement Shock Absorber - Front Right is a high-performance shock absorber designed to replace the original equipment shock absorber on the BMW 530i. It features a monotube design which provides superior damping control and a higher level of performance than conventional twin-tube designs. The shock absorber is made from a special alloy steel which is then zinc plated for superior corrosion resistance. The shock absorber is designed to provide a smoother ride, improved handling, and increased stability for the vehicle.