50.75 In.H-W 4.5 In.L Alu Intake Shutter Dampr For Nominal Duct Diameter Not Applicable Frame Material Aluminum Number of Panels 1 Maximum Air Velocity 2250 fpm Overall Height 50 3/4 in Rough Opening Diameter 49 in Rough Opening Shape Square Fits Fan Diameter 48 in For Duct Shape Not Applicable Free Area 12.3 sq ft Overall Width 50 3/4 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 49 in