44 In.H-W 4.5 In.L Alu Ceiling Shutter Dampr, For Nominal Duct Diameter Not Applicable, Frame Material Aluminum, Number of Panels 1, Maximum Air Velocity 2250 fpm, Overall Height 44 in, Rough Opening Diameter 42 in, Rough Opening Shape Square, Fits Fan Diameter 42 in, For Duct Shape Not Applicable, Free Area 9.6 sq ft, Overall Width 44 in, Frame Material Thickness 0.1 in, Overall Length 4 1/2 in, Connection Type Not Applicable, Frame Depth 1 5/8 in, Rough Opening Length 42 in