Glixal ATMT1-005 High Performance GY6 50cc to 60cc 44mm Big Bore Cylinder Kit with Piston for 139QMB 139QMA Scooter Moped ATV 1.Inner Diameter of Cylinder: 44mm 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 5. High Performance 44mm Cylinder Rebuild Kit for GY6 49cc 50cc 60cc engine