Roof Curb Adapter Adapter Type Reducer For Fan Base Size 25 1/2 in For Curb Size 24 in Material Steel For Fan Type Downblast Fans Filtered Supply Fans Upblast Fans Curb Side Width 24 in Fan Side Width 25 1/2 in Finish Galvanized Function Adapts a 26 in Fan Base to Fit 24 in Roof Curb Includes (8) 1/4-20 Tinnerman Speed Nut (8) 1/4-20 x 3/4 Bolts Metal Material Thickness 18 ga Number of Fasteners per side 2 Overall Height 5 in Top Flange Height 2 1/2 in