63 In.H-W 12.8 In.L Squ Stl Mtrzd Cntrl Dampr For Nominal Duct Diameter Not Applicable Damper Application Motorized Number of Panels 2 Overall Height 63 in Overall Length 12 3/4 in Rough Opening Shape Square For Duct Shape Square Overall Width 63 in Frame Material Thickness 14 ga Blade Material Galvanized Steel Maximum Air Pressure 4 in wg Overall Diameter 63 in Rough Opening Length 61 in Rough Opening Width 61 in Damper Type Dynamic Maximum Air Velocity 3500 fpm