19.8 In.H-W 14.5 In.L Squ Mtrzd Contrl Dampr For Nominal Duct Diameter 20 in Damper Application Motorized Number of Panels 1 Overall Height 19 3/4 in Overall Length 14 1/2 in Rough Opening Shape Square For Duct Shape Square Overall Width 19 3/4 in Frame Material Thickness 14 ga Blade Material Galvanized Steel Maximum Air Pressure 4 in wg Rough Opening Length 20 in Rough Opening Width 20 in Maximum Air Velocity 3500 fpm Nameplate Voltage 100/240V AC