This fits on a 1″ crankshaft the other end is 3/8″. The crankshaft must be threaded to accept a bolt to hold clutch onto shaft. Comes with two set screws and 1/4″ key. This is a heavy duty clutch designed for standard live axle karts using up to 18″ tall tires.The 10t sprocket allows you to achieve a desired gear ratio for good pulling power, recommend using at least a 60T drive sprocket.For larger tire application and extreme riding you will need a torque converter.Not available for #35 chainDimensions: outside diameter 4 3/4″ total width 3″ clutch back to sprocket is 2 1/2″Package Includes:1X Centrifugal Go Kart ClutchAs the picture shown