24 In.H 48 In.W Drnbl Extrd Alu Combo Dmpr Louver Type Combination Frame Type Hat Channel Outside Height 23 1/2 in Outside Width 35 1/2 in Rough Opening Height 24 in Rough Opening Width 36 in Louver Maximum Intake 1 444 cfm Maximum Exhaust 2 269 cfm Flange Width Not Applicable Free Area 2.1 sq ft Beginning Point of Water Penetration 1 118 fpm Maximum Air Velocity 3 500 fpm Blade Angle 45 Degrees Material Aluminum Inside Height 22 1/2 in Inside Width 33 3/4 in Number of Blades 4