The VERTEX 2-Stroke Pistons are made through gravity casting from an aluminum alloy with an 18% silicon content. The silicon reduces thermal expansion at operating temperatures, making the piston less susceptible to rattling and breakage. Moreover, silicon imparts better wear characteristics to the pistons, thereby extending their lifespan. The kit is delivered with the piston, including piston ring(s), piston pin, and piston pin retainer! Available in 2-stroke versions: Replica = piston corresponds to the original form, Race = performance-enhancing piston, Pro Race = forged special piston.