The VERTEX TopEnd Piston Kit for HONDA Pro HC models is designed to withstand the increased cylinder pressure of 4-stroke engines. These pistons are forged from the highest quality aluminum alloy (2618) to endure the internal pressure of the engine. Each VERTEX piston features a MOS2 coating on the piston skirt to reduce wear. VERTEX is the original equipment manufacturer for some of the largest motorcycle brands and is trusted by many factory teams in the MXGP circuit. The VERTEX Top-End Piston Kit saves you time and money as it contains everything you need for a piston replacement. The kit includes a piston, cylinder gasket set, and timing chain! The 4-Stroke Pro Replica model features a forged piston that matches the original design, while the Pro HC version is a forged specialty piston that offers higher compression and performance enhancement.