The Bilstein B3 07-13 BMW X5 Replacement Rear Air Suspension Spring (W/ Self-Leveling Suspension) is a direct replacement for the original air suspension spring found in BMW X5s from 2007-2013. This spring is designed to provide a smoother ride and improved handling, while also providing self-leveling suspension. It is made of a high-quality steel construction for durability and long-term reliability. It is also designed to be easy to install and comes with all necessary hardware.