The Bilstein 14-17 BMW 535i GT B3 OE Replacement Air Suspension Spring is a rear suspension spring designed to replace the original equipment spring on the BMW 535i GT. This spring is made from high-quality materials and is designed to provide superior ride comfort and handling. It is also designed to be a direct replacement for the original equipment spring, making installation easy. This spring is designed to improve the overall performance of the vehicle and provide a smoother ride.