19 In.H-W 6 In.L Aluminum Gable Shutter Damper, For Nominal Duct Diameter Not Applicable, Frame Material Aluminum, Number of Panels 1, Maximum Air Velocity 2500 fpm, Overall Height 19 in, Rough Opening Diameter 16 1/2 in, Rough Opening Shape Square, Fits Fan Diameter 16 in, For Duct Shape Not Applicable, Free Area 1.4 sq ft, Overall Width 19 in, Frame Material Thickness 0.8 in, Overall Length 6 in, Connection Type Not Applicable, Frame Depth 1 1/2 in, Rough Opening Length 17 in