GOOFIT 57.4mm Bore Cylinder Kit with Piston for 4 Stroke GY6 150cc ATV 157QMJ Engine Fit for 4 stroke GY6 150cc Engines Package including cylinder head,gaskets,piston,piston rings,clips,wrist pin Inner Diameter of Cylinder: 57.4mm,outer Diameter of Piston Pin: 15mm Arrival within 1-2 days (Sold by GOOFIT and Fulfilled by Amazon) Arrival within 7-15 days (Ships from and sold by GOOFIT)