Naraku 107mm Sport Clutch for 2 Stroke and 4 Stroke 50cc engines. Applications include QMB139 4 stroke engines, Genuine buddy 50 and Roughhouse 50, (Jog) style and Vertical fits (Dio) style 2 stroke engines.The Naraku Sport Clutch Engages at a higher RPM than a stock clutch, allowing for better take-off from stops.Please see our Warranty & Returns Policy. Outer Diameter: 107mm Kevlar Reinforced Clutch Shoes Engages 1500-2000 RPM Higher Than a Stock Clutch