7-9 In.dia SS Barometric Draft Control Damper Application Barometric Draft Control For Nominal Duct Diameter 7 in 8 in 9 in Frame Material Steel Number of Panels Not Applicable Maximum Air Velocity Not Applicable Overall Height 8 3/4 in Rough Opening Diameter 8 in Rough Opening Shape Round Fits Fan Diameter Not Applicable For Duct Shape Round Free Area Not Applicable Overall Width 8 3/4 in Frame Material Thickness 20 ga Overall Length 11 in Connection Type Press Fit