The Koni Special Active Shock FSD 99-05 BMW 3-Series E46 RWD Rear - Sedan Only is a performance shock absorber designed for the BMW 3-Series E46 RWD Rear - Sedan Only. It features Koni's Frequency Selective Damping (FSD) technology, which allows the shock absorber to adjust its damping forces based on the frequency of the road surface, providing superior ride comfort and stability. The shock absorber is adjustable, allowing for fine-tuning of the damping forces to suit individual driving styles. It is also designed to be durable and long-lasting, making it an ideal choice for performance vehicle enthusiasts.