Zinc-plated for corrosion resistance. Includes spring washers M6 - M8; penny washers M6 x 18 x 1.3mm and M8 x 25 x 1.6mm; flat washers M3 x 6, M4 x 8, M5 x 10, M6 x 13, M8 x 16, M10 x 20, M12 x 23mm. Handy storage case with compartments.