High quality stainless steel material, high hardness, good resistance to corrosion and oxidation, for a long lifespan Type of head: cylindrical head 6 hollow sides; Kit consists of 150pccs screws and 60pccs nuts thread: m2.5; Length: 8/12/16/30mm; Standard: metric The thread is very precise and clean. It can make your job easier. Our screws and nuts comply with the normalized metric system used widely in domestic and office devices, communication equipment, assembly of ships and other industrial machines