Roof Curb, For Fan Base Size 19 in to 20 1/2 in, Curb Height 24 in, Curb Inside Width 14 1/2 in to 18 in, Curb Outside Width 17 1/2 in to 22 in, Material Steel, Standards NFPA 96, UL 705, UL 762, For Use With NFPA 96, UL 705, UL 762, Adjustability Adjustable, Ventilation Type Ventilated, Application Commercial Kitchen, Curb Inside Length 14 1/2 in to 18 in, Curb Shape Square, Features Flashing Flange, Finish Galvanized, Flashing Flange Width 5 in