27 In.H-W 12 In.L Squ Alu Mtrzd Cntrl Dampr, For Nominal Duct Diameter Not Applicable, Damper Application Motorized, Number of Panels 1, Overall Height 27 in, Overall Length 12 in, Rough Opening Shape Square, For Duct Shape Square, Overall Width 27 in, Frame Material Thickness 0.1 in, Blade Material Aluminum, Maximum Air Pressure 4 in wg, Overall Diameter 27 in, Rough Opening Length 25 in, Rough Opening Width 25 in, Damper Type Dynamic, Maximum Air Velocity 3500 fpm