Given the higher cylinder pressure in 4-stroke engines, the piston is generally made from forged parts. To withstand the internal pressure of the engine, VERTEX pistons are forged from the highest quality aluminum alloy (2618). To reduce wear, each VERTEX piston has a MOS2 coating on the piston skirt. VERTEX is an OEM supplier for some of the largest motorcycle manufacturers, and many factory teams in MXGP rely on VERTEX's performance. The piston is delivered including piston ring(s), piston pin, and piston pin lock! Piston type for 4-strokes: Pro Replica = forged piston matches the original shape, Pro HC = forged special piston (higher compression and performance enhancing). This VERTEX Piston Kit for Yamaha and Fantic offers outstanding performance, durability, and reliability that is trusted by professionals and enthusiasts alike. Made from a high-quality 2618 aluminum alloy, it ensures superior resistance to wear and tear, thanks to its MOS2 coating. Ideal for 4-stroke engines, it includes all necessary components for a complete setup: piston rings, piston pin, and piston pin locks. Whether for racing or daily riding, this piston kit guarantees enhanced engine efficiency and longevity.