The VERTEX TopEnd Piston Kit for KTM and HQV Pro Replica bikes is designed to endure the high cylinder pressure of 4-stroke engines. Each VERTEX piston is forged from premium-grade aluminum alloy (2618) to withstand internal engine pressure. To reduce wear, every VERTEX piston features a MOS2 coating on the piston skirt. VERTEX is an OEM supplier for several leading motorcycle manufacturers and trusted by many factory teams in MXGP racing. The VERTEX Top-End Piston Kit saves you time and money by including everything needed for a piston replacement. Each kit comes with a piston, cylinder gasket set, and timing chain. Piston Configurations for 4-Stroke: Pro Replica = forged piston matching the original form, Pro HC = forged special piston (higher compression and performance-enhancing).