All pistons are heat-treated with a T-5 hardening and tempering cycle.All piston skirts are coated with a high-tech Molybdenum Disulphite coating for faster break-in time and increased piston life. Cast piston kits are gravity-cast aluminum alloy (not forged) with 18% silicone content, which produces an extremely light but very strong piston. Forged pistons are forged from 2618 aluminum for superior strength and durability. Forged High Compression pistons improve power and torque across entire rpm range. Big Bore pistons increase engines displacement, torque, and peak horsepower. Forged Replica pistons are forged OE replacements. Replica pistons and all rings are OEM replacements. Kits include piston, rings, wrist pin and circlips. Top end piston kits include piston, rings, wrist pin, circlips and top end gaskets. Replacement two-stroke piston rings sold individually; 4-stroke piston rings sold as a set. PISTON VERSIONS Replica Cast piston in original OE form. Race Cast piston developed with Vertex technology. Pro Forged piston. Replica BB Cast piston in original OE form for big bore cylinder. Pro-Replica Forged piston in original OE form. Pro-BB Forged piston in original OE form for big bore cylinder. Pro-Race Forged piston developed with Vertex technology. Pro-HC Forged piston developed with Vertex technology and high compression.