34 In.H 24 In.W Non-Drnbl GSteel Intake Louver Louver Type Stationary Blade Frame Type Flanged Frame Depth 4 in Mounting Style Surface Mount Outside Height 34 in Outside Width 24 in Rough Opening Height 30 in Rough Opening Width 21 in Louver Maximum Intake 2 625 cfm Maximum Exhaust 3 750 cfm Maximum Outside Width 40 in Minimum Outside Width 25 in Flange Width 2 in Free Area 2.8 sq ft Beginning Point of Water Penetration 766 fpm Maximum Air Velocity 3000 fpm