Round Motrzd Damper wController,6 in, For Nominal Duct Diameter 6 in, Damper Application Motorized, Number of Panels 1, Overall Height 9 7/8 in, Overall Length 9 3/4 in, Rough Opening Shape Round, For Duct Shape Round, Overall Width 6 in, Blade Material Galvanized Steel, Overall Diameter 6 in, Rough Opening Length 5 1/2 in, Rough Opening Width 5.6 in, Damper Type Dynamic, Nameplate Voltage 24V DC, Rough Opening Diameter 5.6 in, Includes Envirosense Ventilation Control