VERTEX Piston Kit - 66.45 mm - Banshee YFZ350 23607250Piston Kit 66. 45 mm Banshee YFZ350 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, Cast piston is gravity cast aluminum alloy (not forged) with 18% silicone content, Piston kit includes piston, rings, wrist pin and circlips, For use with Hot Rods Stroker crankshaft.