Changchun Yutai Optics supplies custom metallized mirrors coated with either Aluminum (Al), Silver (Ag) or Gold (Au).For the Total reflection mirrors coated with Aluminum, Aluminum over coated with MgF2 or SiO2 and aluminum coating only are offered as standard. MgF2 protection coating prevents damage and oxidation of aluminum, but reduces reflection slightly compared with the aluminum coating only. Usually, MgF2 protection coating is designed for maximum reflectance at visible.