The VERTEX 2-Stroke Pistons are gravity cast from an aluminum alloy containing 18% silicon. This silicon content reduces thermal expansion at operating temperatures, providing the advantage of less susceptibility to piston slap and fractures. Silicon also endows the pistons with better wear characteristics, thereby extending the lifespan of the pistons. The piston kit comes complete with piston rings, piston pin, and piston pin retaining clips. Various 2-stroke piston designs are available: Replica (matches the original form), Race (performance-enhancing design), and Pro Race (forged special piston).