4 inch Air Vents Cover Made of 304 stainless steel better than 201 material Black baked paint process ,More anticorrosive and rust The dryer vent cover is designed a round flat cover with 45°Louver to prevent rainwater from flowing in; and built in fine mesh grille to stop sundries and small pet from entering the house. The air vent is designed with a louver grille cover, windproof and rainproof. Ideal for all tumble dryer vent pipes / hoses, bathroom vents & extractors, air conditioning units, kitchen fans & vents, all home wall vents, heat transfer and ventilation systems, gas & electric dryers, cooker hood extractors, as well as a wide variety of industrial uses. A perfect replacement of the old or rust vent cap for your house. Flat air vents is made of high quality 304 stainless steel; 304 stainless steel is much better than 201 material, sturdy durable, anti-aging and corrosion resistant. The Air Vent grille cover is designed a round flat cover with 45°Louver to prevent rainwater from flowing in; and the air vent built in fine mesh grill to stop sundries and small pet from entering the house.