Intake Louver Fixed Drainable 48H x 18W

51 In.H 21 In.W Drnbl Extrd Alu Intake Louver Louver Type Stationary Blade Frame Type Flanged Frame Depth 4 in Mounting Style Surface Mount Outside Height 47 1/2 in Outside Width 17 1/2 in Rough Opening Height 48 in Rough Opening Width 18 in Louver Maximum Intake 2 843 cfm Maximum Exhaust 4 065 cfm Maximum Outside Width 20 1/2 in Minimum Outside Width 20 1/2 in Flange Width 1 1/2 in Free Area 3 sq ft Beginning Point of Water Penetration 1 031 fpm Maximum Air Velocity 3500 fpm