Roof Curb For Fan Base Size 34 1/2 in Curb Height 12 in Curb Inside Width 30 in Curb Outside Width 33 in Material Steel Standards UL 705 For Use With 34 1/2 in Square Base Adjustability Fixed Ventilation Type Nonventilated Application General Exhaust Curb Inside Length 30 Curb Outside Length 33 in Curb Shape Square Damper Tray Size 27 1/2 in x 27 1/2 in Features Flashing Flange One Welded Corner Wood Nailer Finish Galvanized Flashing Flange Width 2 in