Athena Pistone Set For over 10 years Athena has been working with the best motocross racing teams in the world and has developed in collaboration with you pistons. All piston models are made of aluminum alloys and have a perfect blend of nickel, copper and silicon. Designed and built with the best technologies available. The careful selection of high quality raw materials together with the most advanced engineering techniques guarantees lightness and resistance of the piston, for better engine performance and durability. Forged pistons are heat resistant and more durable than cast pistons. Athena piston kits are complete with rings, pins and clips. Piston Diameter: 100.94mm (A) Butt Material: Forged Piston Pin Diameter 22mm Compression Rate: Matches OE Piston