45 In.H-W 6.5 In.L Extrd Alu Backdraft Dampr Damper Application Backdraft For Nominal Duct Diameter Not Applicable Frame Material Aluminum Number of Panels 2 Maximum Air Velocity 3250 fpm Overall Height 45 in Rough Opening Diameter 42 1/2 in Rough Opening Shape Square Fits Fan Diameter 42 in For Duct Shape Not Applicable Free Area 10.3 sq ft Overall Width 45 in Frame Material Thickness 0.8 in Overall Length 6 1/2 in Connection Type Not Applicable Frame Depth 3 in