VERTEX 2-stroke pistons are gravity-cast from an aluminum alloy containing 18% silicon. The silicon reduces thermal expansion at operating temperatures. This advantage makes the piston less prone to clatter and breakage. Furthermore, silicon gives the pistons enhanced wear characteristics, thereby extending the piston life. The kit includes pistons, piston rings, piston pin, and piston pin clips. Piston types for 2-stroke engines include: Replica (matches the original shape), Race (performance-enhancing design), and Pro Race (forged special piston).