Round Bypass Zoning Damper,Steel,8 In. dia, For Nominal Duct Diameter 8 in, Damper Application Zoning, Number of Panels Not Applicable, Overall Height 9 5/8 in, Overall Length 11 1/2 in, Rough Opening Shape Round, For Duct Shape Round, Overall Width 8 in, Frame Material Thickness Not Applicable, Blade Material Galvanized Steel, Maximum Air Pressure Not Applicable, Overall Diameter 8 in, Rough Opening Length 8 in, Rough Opening Width 8 in, Damper Type Dynamic, Maximum Air Velocity Not Applicable