The Koni Special Active Shock FSD 03-10 BMW X3 / X4 (F25) Front Left is a high-performance shock absorber designed to provide improved handling and stability for BMW X3 and X4 vehicles. It features Frequency Selective Damping technology, which allows for adjustable damping forces based on the frequency of the road surface. This results in improved ride comfort and handling, as well as increased safety and control. The shock absorber also features a rebound valve, which helps to reduce body roll and improve cornering performance. This shock absorber is designed to provide superior performance and is an ideal choice for those looking for improved handling and stability.