24 In.H 27 In.W Drnbl Extrd Alu Combo Dmpr Louver Type Combination Frame Type Hat Channel Outside Height 29 1/2 in Outside Width 29 1/2 in Rough Opening Height 30 in Rough Opening Width 30 in Louver Maximum Intake 1 724 cfm Maximum Exhaust 2 475 cfm Flange Width Not Applicable Free Area 2.2 sq ft Beginning Point of Water Penetration 1 118 fpm Maximum Air Velocity 3 000 fpm Blade Angle 45 Degrees Material Aluminum Inside Height 28 1/2 in Inside Width 27 3/4 in Number of Blades 6