23 In.H-W 12 In.L Squ Alum Mtrzd Contrl Damper For Nominal Duct Diameter Not Applicable Damper Application Motorized Number of Panels 1 Overall Height 23 in Overall Length 12 in Rough Opening Shape Square For Duct Shape Square Overall Width 23 in Frame Material Thickness 0.1 in Blade Material Aluminum Maximum Air Pressure 4 in wg Overall Diameter 23 in Rough Opening Length 21 in Rough Opening Width 21 in Damper Type Dynamic Maximum Air Velocity 3500 fpm