Aeroflow's bump cup is designed to be used with Pro Shocks (9/16" shaft) and hides your bump stop or shim stack from the view of your competition. Utilized with shock body pointed in the up or downward position and clears both large body and adjustable shocks. The threaded base fits in place of the jam nut, utilizing a 1" or #10 AN hex to secure the shock end bearing. Black anodized finish.