Bilstein SL Series - Suspension Shock Absorber - 33-321899Bilstein SL Series shock absorbers feature a 46mm piston, steel construction, and a smooth body designed for motorsports applications. These shock absorbers are available in a variety of lengths, valve settings and can be converted to a coilover design (kit sold separately). SL Series shock absorbers are ideal for racers whose sanctioning rules do not allow or require rebuild capability. 46mm Monotube Shock Absorber