17 Tooth 3/4'' Bore #35 Chain The SS series is the most popular style clutch used by the O.E.M.since its introduction in 1970. This clutch comes in many different configurations to meet any O.E.M. requirements. Keystock is not included. Use AZ_8454 key. These clutches are not drilled and tapped for set screws. Use a large washer and a bolt in the crank to secure the clutch.