Clutch. Most commonly (though not exclusively) used for 33cc, 37cc, 39cc, 47cc and 49cc 2-stroke air and liquid cooled engines. Popularly applies to a wide range of pocket bikes, mini dirt bikes, mini quads, mini choppers, stand-up / sit-down scooters as well as many other powersport and personal transportation products. This clutch works with our 10P9040 complete engine.