VERTEX 2-stroke pistons are gravity cast from an aluminum alloy with 18% silicon content. The silicon reduces thermal expansion at operating temperatures, making the piston less prone to rattling and breakage. Additionally, silicon enhances the piston's wear resistance, thereby extending the lifespan of the piston. The piston kit includes piston ring(s), piston pin, and piston pin retainer! Piston types for 2-stroke: Replica = piston matches original form, Race = performance-enhancing piston design, Pro Race = forged special piston.