4 Inch Duct Connector Flange Metal Straight Pipe Exhaust Hose Flange | eBay
Drillfast | Duct Flange
Ruskin Titus India
Steel, For 16 in Duct Dia, Angle Flange Adapter - 29RN93|8010000153 - Grainger
Vent Systems 4" inch Air Vent Duct Connector Flange Straight Ventilation Pipe Plastic Ducting Connector Plate for Cooling Heating Ventilation System HVAC 4" inch - Pack of (1) - Amazon.com
Made in USA - 6″ ID, Galvanized Duct Flange Adapter - 03233665 - MSC Industrial Supply