This is the Crankshaft for the O.S. Max XZ-B Engine (OSMG2050). The crankshaft fits into the crankcase and the clutch nut, flywheel, bearings and con rod mount to this shaft. FEATURES: Tungsten-weighted silicone filled crankshaft creates optimum balance for consistent low and mid speed torque INCLUDES: One Crankshaft for the O.S. Max .21 XZ-B Engine SPECS: Length: 76mm (2.99") Crankshaft threading: 1/4-28 Pilot shaft diameter: 5mm (.20") Crankshaft diameter: 7mm (.28") (flywheel position)