Galvanized sheet air ducts basically have the characteristics of stainless steel air ducts, but the price is only two-thirds or even lower than that of stainless steel air ducts. Galvanized sheet air ducts are mainly coated with a layer of zinc on the iron sheet of the duct to provide protection for the iron sheet. After passivation treatment, dyeing or coating with light protectants, the protective and decorative properties of zinc coatings can be significantly improved.