The Bilstein 04-07 BMW 525i B3 OE Replacement Coil Spring - Front is a direct replacement for the original equipment coil spring on a 2004-2007 BMW 525i. It is designed to provide a comfortable, yet sporty ride, while maintaining factory ride height. This coil spring is made from high-quality steel for superior strength and durability, and is corrosion-resistant for long-lasting performance. It features a progressive spring rate for improved handling and a comfortable ride, and is backed by a limited lifetime warranty.