PROX pistons are precision machined on the latest, state of the art CNC equipment. The same low-expansion, low-friction piston alloy is used as is used for all major Japanese engine manufacturers. PROX Piston Kits are a first class solution to replace the original piston in your Motorcycle, Scooter, Moped, ATV, Personal Watercraft, etc. PROX Piston Kits for sleeved cylinders are available in standard size and a wide range of oversizes. The availability of oversizes up to 2mm significantly helps to increase the lifespan of a cylinder by offering more re-boring possibilities. PROX pistons for plated cylinders come in standard size, as well as in A, B, C, D+ oversizes. Take advantage of the additional oversizes to extend the lifespan of plated cylinders. All PROX Piston Kits are supplied complete with Piston Rings, Wrist Pin and Circlips, ready to install!