Performance 6-Groove Adjustable Secondary Sliding Sheave, Racing Torque Driver GY6 125cc 150cc 152QMI 157QMJ Engine This adjustable torque driver allows adjustment of the acceleration of CVT transmission to suit your needs. 3 straight grooves provide quicker takeoff; 3 bent grooves offer higher speed. Clutch seat outer diameter: 141mm. Pulley needle bearing: HK202918RS. Fits GY6 125cc, 150cc, and 200cc and karts with 152QMI and 157QMJ based engines.Also fits RZR 170cc engine. Compatibility Disclaimer: This is an aftermarket replacement part.Any brand names or model designations mentioned are used solely for the purpose of demonstrating compatibility.