... Materials: stainless steel 304 or carbon steelGalvanized pentagon Hole Air Filter Perforated Mesh Material: mild steel, galvanized steel ... , stainless steel, aluminum, brass etc. Hole style: round, rectangular, elliptical, diamond,hexagonal, cross, slotted ... times2.Used for primary flitration system of center air confition3.Usable for ventilation filter, especially endurable ...