Piston Kit - 4.075" Bore - 4.625" Stroke - 11.5:1 CR - 121" M8 2618-T6 forged construction provides better aligned grain flow and higher tensile strength to provide durability, even in high-performance builds, Skirt coating reduces opertating friction and wear , Offset pins reduce piston rock and minimize operating noise, Skirt notches for optimal at bottom dead center, Accumulator groove taps combustion gases below the top ring to promote more consistent, positive ring seal and performance, Inlcudes two pistons, premium ring packs, wrist pins and wire locks