Heavy Duty Plastic; Bird Proof Louvered Vent Cover Sized For Universal Dryer Vents Or Stove Vents. Pipe Opening is 6 inch. Outside Dimension is 7-7/8'' with a depth of 5/8'' inches. 1/2" Square Openings Melting Point is 325 F+ Calcium Filled Polypropylene.6" is for the vent it attaches to.