304 Stainless SteelDURABLE MATERIALS:The exterior dryer vent cover is made of 304 Stainless Steel.The Stainless Steel dryer vent cover can be used for long years and perfect for air exhaust.Different from frangible plastic dryer vent cover,our dryer vents for houses are more durable,anti-rust,anti-heat,anti-aging and corrosion resistant .AUTOMATIC DESIGN:The easy moving outside lamellas of the dryer vent cover outdoor can provide maximum volume flows.When any pressure is applied from the inside(work with very low air pressure), the ventilation duct grille can easily open the flaps and when it not in use, the one-way shutters will automatically close to keep rain,snow or others out.MULTIPLE USAGES:The outside vent cover is suitable for ventilation ducts, bathroom vents and smoke extraction equipment, air conditioners, kitchen fans and vents, all home wall vents, heat transfer and ventilation systems, range hood extractors, and part of industrial uses,which can prevent debris into the house.EASY TO INSTALL:Insert the nozzle into the ventilation tube.Then use the four supplied stainless steel screws to fix 4 inch dryer vent hood on the wall. Our exterior wall vent cover comes with four screws.(Please power off before installation.)