Hard-22mm-Wide shoulder gasket used on forged clamps only-RG-4-FG-H, Medium-20mm-Great all-rounder used on cast/forged clamps-RG-4-M, Medium-22mm-Wide shoulder gasket used on forged clamps only-RG-4-FG-M, Soft-18mm-Used on cast A4 clamps only – RG-4-S