Piston Series Pro SeriesCylinder Head RMZ 250Bore Diameter 80.00 MMCompression Ratio Actual 13.00:1Piston Head Type DishPiston Volume 12.00 CCPiston Material 2618Forging Type FSRPiston Average Weight 170 GRRing Set Included YesTop Compression Ring Thickness 0.0360 INOil Ring Thickness 0.0585 INWrist Pin Material 9310 Nickel Carbon Steel AlloyWrist Pin Outer Diameter 0.630 INWrist Pin Wall Thickness 0.120 IN