The ProX cast piston kit offers designs that are typically similar to OEM/stock configurations, with customization options to improve performance. Cast pistons are very stable and are manufactured through gravity casting using an aluminum alloy with approximately 18% silicon content. Silicon helps reduce thermal expansion, thereby enhancing performance. ProX two-stroke pistons are available for cast iron cylinders and Nikasil cylinders, with a range of sizes classified as A/B/C/D, each increasing by 0.01 millimeters in diameter.