These nuts are suitable for fastening most machinery and equipment.Zinc–plated steel nuts resist corrosion in wet environments.Black ultra–corrosion–resistant coated steel nuts are more corrosion resistant in wet environments than zinc-plated steel nuts. Also known as black luster nuts.Black–oxide steel nuts have a dark surface color and are mildly corrosion resistant in dry environments.

In short its reliability and stability increases when such coatings are given, it also ensures in increased life of the nut. This coating protects the nut from rusting and corrosion that might take place due to change in external environments.