56.1 In.H Alum Vertical Intake Shutter Frame Material Aluminum Number of Panels 2 Maximum Air Velocity 2000 fpm Overall Height 56 1/8 in Fits Fan Diameter 48 in Free Area 18.4 sq ft Overall Width 54 3/8 in Frame Depth 2 in Blade Material Aluminum Flange Width 1 3/8 in