Due to the higher cylinder pressure in 4-stroke engines, VERTEX pistons are generally made from forged pieces. To withstand the internal pressure of the engine, the pistons are forged from high-quality aluminum alloy (2618). To reduce wear, each VERTEX piston features a MOS2 coating on the piston skirt. VERTEX is an original equipment manufacturer for some of the largest motorcycle manufacturers, and many factory teams in the MXGP trust in the performance of VERTEX. The VERTEX Top-End Piston Kit saves you time and money, as this set includes everything you need for the piston replacement. Contents: Piston kit including cylinder gasket set and timing chain! Piston design for 4-stroke: Pro Replica = forged piston corresponds to original form, Pro HC = forged special piston (higher compression and performance-enhancing).