46 In.H 28 In.W Non-Drnbl GSteel Intake Louver Louver Type Stationary Blade Frame Type Flanged Frame Depth 4 in Mounting Style Surface Mount Outside Height 46 in Outside Width 28 in Rough Opening Height 42 in Rough Opening Width 24 in Louver Maximum Intake 4 290 cfm Maximum Exhaust 6 125 cfm Maximum Outside Width 46 in Minimum Outside Width 28 in Flange Width 2 in Free Area 5.6 sq ft Beginning Point of Water Penetration 766 fpm Maximum Air Velocity 3000 fpm