These Forgefix Hexagon Nuts are bright Zinc Plated for increased corrosion resistance The hexagonal shape is designed to be driven by a wrench spanner and provides excellent torque when done so Zinc coatings prevent oxidation of the protected metal to create a longer lasting finish It does this by forming a barrier and by acting as a sacrificial anode if this barrier is damaged Zinc oxide is a fine white dust that in contrast to iron oxide does not trigger a breakdown of the substrates surface integrity as it is formed The zinc oxide if left intact can act as a barrier to further oxidation in a way similar to the protection afforded to aluminum and stainless steels by their oxide layers