40 In.H-W Aluminum Ceiling Truss Damper Frame Material Aluminum Number of Panels 1 Maximum Air Velocity 1500 fpm Overall Height 42 in Rough Opening Shape Rectangular Fits Fan Diameter 42 in Free Area 8.2 sq ft Overall Width 40 in Frame Material Thickness 0.1 in Frame Depth 1 3/8 in Rough Opening Length 40 in Maximum Pressure 1 in wc Rough Opening Width 38 in Blade Material Aluminum Closure Type Gravity Flange Width 1 5/8 in