Medium-22mm-Great all-rounder used on cast/forged clamps-RG-6-M, Medium-22mm-Used on special Putzmeister clamps with 166mm O.D. ends-RG-6-M-166, Medium-24mm-Thick walled gasket used on forged clamps only-RG-6-M-TH, Soft-22mm-Great all-rounder used on cast/forged clamps-RG-6-S