Louver,Wall Opening 18x18In,Galvannealed 4FZG3

18 In.H 18 In.W Non-Drnbl GSteel Modulr Louver, Louver Type Stationary Blade, Frame Type Hat Channel, Frame Depth 4 in, Mounting Style Flush Mount, Outside Height 17 1/2 in, Outside Width 17 1/2 in, Rough Opening Height 18 in, Rough Opening Width 18 in, Louver Maximum Intake 744 cfm, Maximum Exhaust 1,063 cfm, Maximum Outside Width 17 1/2 in, Minimum Outside Width 17 1/2 in, Flange Width Not Applicable, Free Area 0.9 sq ft, Beginning Point of Water Penetration 709 fpm