ScootsUSA GY6B Variator Drive Face - 123mm Fixed Drive Face for 150cc GY6B 4-stroke ZNEN engines commonly found in Lance Phoenix, Flyscooters Cadenza, ZNEN ZN150T-18, Xingyue ITA-150, Motorino Cassini, CMS Prodigy, BMS Pathfinder and many more. Splined Inner Diameter (peak to peak): 15mm Splined Inner Diameter (valley to valley): 16.7mm Number of Splines: 21 Outer Diameter: 123mm