CVtech Trail Bloc Primary Clutch with HD retaining bolt, calibrations are for ATVs not UTVs Solid upgrade over the factory unlocked primary clutch, this is a straight bolt on replacement. Locked sheaves, smaller one-way diameter and more belt grip. This is a great clutch for riders looking for a performance upgrade. This comes preset, some fine tuning may be required to get this 100% Many find these settings to be spot on. We will provide assistance in fine tuning for your riding style. Please allow additional 1-2 day handling time.