8 In.dia Norm Opn Rnd Stel Zone Cntrl Dampr, For Nominal Duct Diameter 8 in, Damper Application Motorized, Number of Panels Not Applicable, Overall Height 4 5/8 in, Overall Length 4 7/8 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