The VERTEX Piston Kit YAMAHA Pro Replica is specially designed to withstand the higher cylinder pressures of 4-stroke engines. Forged from high-quality aluminum alloy (2618), these pistons are crafted to endure the internal pressures of the engine. Each VERTEX piston features a MOS2 coating on the piston skirt to reduce wear. Trusted by some of the biggest motorcycle manufacturers as an OEM provider, VERTEX is also the choice of many factory teams in the MXGP for its outstanding performance. This piston kit includes piston rings, piston pin, and piston pin locks. The 4-stroke version, Pro Replica, is a forged piston that adheres to the original form, while the Pro HC variant is a special forged piston offering higher compression and enhanced performance.