Zinc-plated for corrosion resistance. Small, cylindrical head with tall vertical sides. Includes assorted sizes between M5 x 20 to M8 x 30mm. Handy storage case with compartments. Zinc-plated for corrosion resistance. Small, cylindrical head with tall vertical sides. Includes assorted sizes between M5 x 20 to M8 x 30mm. Handy storage case with compartments.