Oregon 84-004 Max Torque Centrifugal Clutch for 4-Cycle Engine Lawn Mower Replacement Part Six sintered metal shoes engage at 2000 RPM "Ss" type automatic clutch for 4-cycle engines Teeth: 12 / chain size: #35 / Bore: 3/4" Stainless Steel garter spring, works clockwise or counterclockwise, oilite bearings for long life. Works in oil, dirt and water with proper maintenance 3/16" keyway an Allen set screws included