PosMAC (POSCO Magnesium Aluminium Alloy Coated Product) is a ternary alloy coated steel- zinc, magnesium and aluminum- with high corrosion resistance developed with POSCO’s proprietary technology. PosMAC is a corrosion resistant product that has five to ten times stronger resistance than that of a normal hot-dip galvanized steel sheet (GI, GI(H)) with the same coating weight. The steel features good resistance to chemicals, red rust, acid and base when applied to surfaces and points of machining. Its good hardness and high friction factor also provide good anti-galling and workability. Called “rust-free iron,” this product is extensively used for buildings’ inner and outer walls, outdoor units of air conditioners, automotive components and many other applications.