Combination Louver Damper 36x48

36 In.H 48 In.W Drnbl Extrd Alu Combo Dmpr Louver Type Combination Frame Type Hat Channel Outside Height 35 1/2 in Outside Width 47 1/2 in Rough Opening Height 36 in Rough Opening Width 48 in Louver Maximum Intake 3 281 cfm Maximum Exhaust 5 156 cfm Flange Width Not Applicable Free Area 5 sq ft Beginning Point of Water Penetration 1 118 fpm Maximum Air Velocity 3 500 fpm Blade Angle 45 Degrees Material Aluminum Inside Height 34 1/2 in Inside Width 45 3/4 in Number of Blades 7