Due to the higher cylinder pressure of 4-stroke engines, pistons are generally made from forged pieces. To withstand the internal pressure of the engine, VERTEX pistons are forged from the highest quality aluminum alloy (2618). To reduce wear, every VERTEX piston features an 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 the performance of VERTEX. The piston kit includes pistons with piston ring(s), piston pin, and piston pin snap rings! The 4-stroke piston design has two options: Pro Replica = Forged piston corresponding to the original form, Pro HC = Forged special piston (higher compression and performance-enhancing). Choose VERTEX for superior engine performance and durability in all racing conditions.