Piston Kit - 53.95 mm - Gas Gas | Husqvarna | KTM The piston is heat-treated with a T-5 hardening and tempering cycle, The piston skirt is coated with a high-tech Molybdenum Disulphite coating for faster break in time and increased piston life, Gravity-cast aluminum alloy (not forged) with 18% silicone content, Unique cast GP-style race piston with only one compression ring, Piston kit includes piston, ring, wrist pin and circlips