Black concrete nails/steel nails are also called high-quality furniture nails. Flat countersunk head, diamond-shaped pointed head, round shank or slot shank. The material is made of No. 45 steel or No. 60 steel, which is processed by wire drawing, annealing, nail making, quenching and other processes, so the texture is relatively hard. Its function is to nail some harder objects that other nails can't nail. Because the material is very different from ordinary nails, it belongs to special nails. Compared with ordinary nails, it can pierce objects more easily .