23.75 In.H 11.75 In.W 3.7 In.L GStl Fire Dampr Damper Application Fire Frame Material Galvanized Steel Number of Panels 1 Maximum Air Velocity 4000 fpm Overall Height 11 3/4 in Rough Opening Diameter Not Applicable Rough Opening Shape Rectangular Fits Fan Diameter Not Applicable For Duct Shape Rectangular Free Area 1.4 sq ft Overall Width 23 3/4 in Frame Material Thickness 22 ga Overall Length 3 3/4 in Connection Type Not Applicable Frame Depth 3 3/4 in