They are made of carbon steel. They are made of #45 steel or #60 steel. They are processed by wire drawing, annealing, nail making, quenching and other processes, they are hard. Its function is to nail on some hard objects that other nails cannot, becuse the material is very different from ordinary nails, whick belongs to special nails. The hardness of nails is very larde thick and short, and the penetration ability is very strong.