The Koni Special Active Shock 97-03 BMW E39 Wagon 5 Series Rear is a performance shock absorber designed to improve the handling and stability of your BMW 5 Series wagon. It features an adjustable rebound setting, allowing you to fine-tune the suspension to your driving style and conditions. The shock is constructed from a monotube design, which provides superior damping control and a more comfortable ride. It also features a unique valving system that helps to reduce body roll and improve cornering stability. The Koni Special Active Shock is a great choice for those looking to upgrade their suspension and get the most out of their BMW E39 Wagon 5 Series.