Roof Curb, For Fan Base Size 28 1/2 in, Curb Height 12 in, Curb Inside Width 24 in, Curb Outside Width 27 in, Material Steel, Standards UL 705, For Use With 28 1/2 in Square Base, Adjustability Fixed, Ventilation Type Nonventilated, Application General Exhaust, Curb Inside Length 24, Curb Outside Length 27 in, Curb Shape Square, Damper Tray Size 21 1/2 in x 21 1/2 in, Features Flashing Flange, One Welded Corner, Wood Nailer, Finish Galvanized, Flashing Flange Width 2 in