Uxcell 4 Inch Duct Connector Flange Square to Round Interface Metal Straight Pipe Air Duct - Walmart.com
J-Lock Duct Hose Fitting
Amazon.com: Vent Systems 5'' Inch Duct Connector 3 Way Hose Adapter/Splitter for Hose Y-Shape Round Pipe Connector- Extractor Fan - Duct Hose Dryer Vent Y Connector - 5 Inch 3 Way Fitting
IMPERIAL 4-in Galvanized Steel Flexible Duct Connector in the Duct Transitions & Connectors department at Lowes.com
Vintage Air 495920 Vintage Air Replacement Duct Hose Connectors | Summit Racing