24 In.H 24 In.W Non-Drnbl GSteel Modulr Louver, Louver Type Stationary Blade, Frame Type Hat Channel, Frame Depth 4 in, Mounting Style Flush Mount, Outside Height 23 1/2 in, Outside Width 23 1/2 in, Rough Opening Height 24 in, Rough Opening Width 24 in, Louver Maximum Intake 1,342 cfm, Maximum Exhaust 1,918 cfm, Maximum Outside Width 23 1/2 in, Minimum Outside Width 23 1/2 in, Flange Width Not Applicable, Free Area 1.8 sq ft, Beginning Point of Water Penetration 709 fpm