Due to the higher cylinder pressure in 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 kit includes the piston with piston ring(s), piston pin, and piston pin retainer! The 4-stroke piston design: Pro Replica = forged piston corresponds to the original form, Pro HC = forged special piston (higher compression and performance-enhancing). Enhance your KAWASAKI bike’s performance with this top-quality piston kit and experience unrivaled durability and power on the track.