VERTEX 2-stroke pistons are crafted using gravity casting from an aluminum alloy containing 18% silicon. The silicon component reduces thermal expansion at operating temperatures, which helps to minimize piston slap and the risk of fractures. Additionally, silicon enhances the wear resistance of the pistons, thereby extending their lifespan. The kit includes the piston, piston ring(s), piston pin, and piston circlip! There are various piston types available for 2-stroke engines: Replica = piston matches the original shape, Race = performance-enhancing design, Pro Race = forged special piston.