PROX pistons are precision machined on the latest, state of the art CNC equipment. The same low-expansion, low-friction piston alloy 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!