CVT torque converter clutch set, Comet 40 profile. Set includes the Driver and driven pulley (also referred to as primary and secondary). Commonly (though not exclusively) used on 8HP to 18HP gas engines. 40 series drive clutch has a bore size of 1” (1 inch) and the 40 series driven clutch has a bore size of 3/4” (0.75 inch). Commonly used with a 725 length belt in a wide variety of scooters, go karts, dune buggies, ATVs, dirt bikes and other powersport applications.