Roof Curb For Fan Base Size 26 in Curb Height 24 in Curb Inside Width 21 in Curb Outside Width 24 1/2 in Material Steel Standards NFPA 96 UL 705 UL 762 For Use With NFPA 96 UL 705 UL 762 Adjustability Fixed Ventilation Type Ventilated Application Commercial Kitchen Curb Inside Length 21 Curb Outside Length 24 1/2 in Curb Shape Square Features Flashing Flange Finish Galvanized Flashing Flange Width 4 in For Fan Type Downblast Fans Filtered Supply Fans Upblast Fans