35 7/8 In.H-W Aluminum Ceiling Truss Damper Frame Material Aluminum Number of Panels 1 Maximum Air Velocity 1500 fpm Overall Height 30 3/4 in Rough Opening Shape Rectangular Fits Fan Diameter 30 in Free Area 5.4 sq ft Overall Width 35 7/8 in Frame Material Thickness 0.1 in Frame Depth 1 5/8 in Rough Opening Length 28 3/4 in Maximum Pressure 1 in wc Rough Opening Width 33.9 in Blade Material Aluminum Closure Type Gravity Flange Width 1 5/8 in