Roof Curb For Fan Base Size 54 1/2 in Curb Height 12 in Curb Inside Width 50 in Curb Outside Width 53 in Material Steel Standards UL 705 For Use With 54 1/2 in Square Base Adjustability Fixed Ventilation Type Nonventilated Application General Exhaust Curb Inside Length 50 Curb Outside Length 53 in Curb Shape Square Damper Tray Size 47 1/2 in x 47 1/2 in Features Flashing Flange One Welded Corner Wood Nailer Finish Galvanized Flashing Flange Width 2 in