Roof Curb For Fan Base Size 16 in Curb Height 12 in Curb Inside Width 12 1/2 in Curb Outside Width 15 in Material Steel Standards UL 705 For Use With 16 in Square Base Adjustability Fixed Ventilation Type Nonventilated Application General Exhaust Curb Inside Length 11.5 Curb Outside Length 15 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