According to Iranian Mines & Mining Industries Development & Renovation (IMIDRO), the Iranian govern… - Strength and hardness equivalent to 410, corrosion resistance superior to 304 by appropriate addition of Mo, as well as by control of trace elements. – High anti corrosion (salt spray test exceed 2,000 hours) – High hardness (Hv 580-620) – One piece without welding, drilling performance superior to Bi-Metal screws. – Shiny surface without any chemical treatment or coating, conform to the standard made by European Union to preserve the environment. - Self-drilling screws – Roofing screws – Tapping screws – Solar panel screws – Marine application screws Welded Steel Pipe, Seamless Steel Pipe, Carbon Steel Pipe – Shenzhoutong,https://www.tjshenzhoutong.com/