Roof Curb, For Fan Base Size 17 in, Curb Height 12 in, Curb Inside Width 12 1/2 in, Curb Outside Width 15 1/2 in, Material Steel, Standards UL 705, For Use With 17 in square base, Adjustability Fixed, Ventilation Type Nonventilated, Application General Exhaust, Curb Inside Length 12.5, Curb Outside Length 15 1/2 in, Curb Shape Square, Damper Tray Size 9 1/2 in x 9 1/2 in, Features Flashing Flange, One Welded Corner, Wood Nailer, Finish Galvanized, Flashing Flange Width 2 in