this is a carbon steel made hexagon nuts,it is made of carbon steel material,and surface plates nickel,black nickel,white zinc,black zinc different coating.
with high hardness,low temperature resistance,anti-corrosive,anti-rust,wear-resistant those advantages,widely used in home improvement,machine,basic construction and other industries.we also have many other types fastening products,please let us know if you have demand in other types,thanks. and this hex nuts insert nylon rings in,make it anti-slip and can locked very tight on screws. Vernickelte Schraubenmuttern, Kontermuttern, Nägel aus Kohlenstoffstahl, rutschfeste Nylon-Sechskantmutter, selbstsichernde Schrauben, Kappe.