Round Fire/Smoke Damper,GalvSt 7.9 In. dia, For Nominal Duct Diameter 8 in, Damper Application Fire and Smoke, Number of Panels 1, Overall Height 7 7/8 in, Overall Length 16 in, Rough Opening Shape Round, For Duct Shape Round, Overall Width 15 5/8 in, Frame Material Thickness 20 ga, Blade Material Galvanized Steel, Maximum Air Pressure 4 in wg, Overall Diameter 7 7/8 in, Rough Opening Width 8 in, Damper Type Dynamic, Maximum Air Velocity 3000 fpm, Nameplate Voltage 120V AC