Due to the increased 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, each VERTEX piston features a MOS2 coating on the piston skirt. VERTEX is an original equipment manufacturer for some of the biggest motorcycle brands, and many factory teams in the MXGP rely on VERTEX performance. The piston kit includes piston rings, piston pin, and piston pin lock. Piston design 4-stroke: Pro Replica = forged piston corresponds to the original form, Pro HC = forged special piston (higher compression and performance-enhancing). Suitable for KTM, HQV, and HUSABERG models.