VERTEX 2-stroke pistons are gravity cast from an aluminum alloy containing 18% silicon. The silicon reduces thermal expansion at operating temperatures, which makes the piston less prone to rattles and fractures. Additionally, silicon enhances the piston's wear resistance, thereby extending its lifespan. The piston kit includes a piston ring(s), piston pin, and piston pin clip! Piston Types for 2-Stroke: Replica = Piston matches original shape, Race = Performance-enhancing piston design, Pro Race = Special forged piston.