Koni Special (Red) Rear shocks for 2007+ Sprinter 3500 models with single or dual rear wheels. Heavy truck, mono-tube shock absorbers are adjustable, allowing customization of rebound rate. This adjustability is perfect for compensating for vehicles loads. Trucks with lighter loads can turn down the fir mess to decrease ride harness and bounce, while trucks with heavier loads can turn up the firmness to increase vehicle control.