36 In.H 39 In.W Drnbl Extrd Alu Combo Dmpr Louver Type Combination Frame Type Hat Channel Outside Height 41 1/2 in Outside Width 41 1/2 in Rough Opening Height 42 in Rough Opening Width 42 in Louver Maximum Intake 3 413 cfm Maximum Exhaust 4 875 cfm Flange Width Not Applicable Free Area 5 sq ft Beginning Point of Water Penetration 1 118 fpm Maximum Air Velocity 3 000 fpm Blade Angle 45 Degrees Material Aluminum Inside Height 40 1/2 in Inside Width 39 3/4 in Number of Blades 9