Piston Kit Pro Bb D80.97 24637CPiston Kit (Forged Big Bore)Pro BB Forged piston in original OE form for big bore cylinder 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 Forged pistons are forged from 2618 aluminum for superior strength and durability Big Bore pistons increase engines displacement, torque, and peak horsepower Kits