Angle Flange Adapter For Nominal Duct Diameter 18 in Inlet Diameter 18 in Material Stainless Steel Product Type Angle Flange Adapter Material Thickness 20 ga Overall Length 5 in Maximum Pressure Rating 42 in wc Weight 15.2 lb For Duct Height 18 in Flange Inner Diameter 18 1/8 in For Duct Width 18 in Flange Outer Diameter 21 1/8 in Maximum Airflow 12 370 cfm Inside Diameter 18 in Number of Holes on Flange 8 Overall Width 21 1/8 in Bolt Circle Diameter 20 in