The VERTEX 2-stroke pistons are gravity cast from an aluminum alloy containing 18% silicon. Silicon helps to reduce thermal expansion at operating temperatures, making the piston less prone to rattling and damage. Additionally, silicon provides better wear characteristics, thus extending the lifespan of the piston. Each piston kit includes the piston, piston ring(s), piston pin, and piston pin retaining clip! Available in 2-stroke configurations: Replica = piston matches the original form, Race = performance-enhancing piston configuration, Pro Race = forged special piston.