The Koni Special Active Shock FSD 03-10 BMW X3 (E83) Front Left is a performance suspension shock absorber designed to improve the handling and ride quality of the BMW X3 (E83). It features Koni's Frequency Selective Damping (FSD) technology, which allows the shock absorber to automatically adjust the damping rate depending on the frequency of the road surface. This provides a smoother ride with improved handling and cornering. The shock absorber is also adjustable, allowing the user to customize the damping rate to their liking.