Pro-X Piston Kit - 0.25mm Oversize to 64.25mm 4191 Excellent economic alternative when you are looking for an OEM quality replacement piston Mainly manufactured in Japan by reputable Original Equipment Manufacturers to ProX exact specifications and high quality standards Sleeved cylinder piston kits are available in standard size and a Wide range of oversizes Plated cylinder piston kits come in standard size, as well as in A, B, C and D oversizes if available ProX leads the industry in cast and forged pistons made specifically to replace OEM parts