Glixal ATMT1-002 GY6 49cc 50cc 39mm Cylinder Kit Piston Rings Chinese QMB139 139QMA Engine Rebuild Kit Scooter Moped ATV 1.Inner Diameter of Cylinder: 39mm 2.Outer Diameter of Piston Pin: 13mm 3.High Quality Durable Piston Rings 4.Include Cylinder,Piston,Piston Ring,Piston Pin,Piston Pin Clip,Valve Oil Seal,Gaskets,Tensioner Gasket,Exhaust Gasket,Intake&Exhaust Studs,Exhaust Nut