8 Inch to 6 Inch HVAC Duct Reducer & Increaser - Galvanized Sheet Metal Ducting Connector for Airflow, Heating, Cooling, & Air Ventilation System Extra Strength and Fittings - Air Tool Fittings - Amazon.com
IMPERIAL 8-in x 6-in Galvanized Steel Duct Reducer in the Duct Transitions & Connectors department at Lowes.com
Vent Reducing Elbow
Buy Hvac System Air Conditioning Round Duct 120 Degree Elbow Reducer Tee Pipe Fittings from Guangzhou Crown Industrial Co., Ltd., China | Tradewheel.com
Duct Direct | Spiral Pipe & Fittings
Master Flow 6 in. 90 Deg. Round Adjustable Elbow B90E6 - The Home Depot
IMPERIAL Galvanized Steel Round Adjustable 90 Degree Duct Elbow in the Duct Transitions & Connectors department at Lowes.com
IMPERIAL Galvanized Steel Rectangle Duct Stack Head Duct Elbow in the Duct Transitions & Connectors department at Lowes.com
IMPERIAL 3-in x 3-in Galvanized Steel Round Adjustable 90 Degree Duct Elbow in the Duct Transitions & Connectors department at Lowes.com
IMPERIAL Plastic Round Corrugated 90 Degree Duct Elbow in the Duct Transitions & Connectors department at Lowes.com
PATIKIL 6" to 3.5" Duct Reducer Connector, Heating Cooling Ventilation Tube Fire-Resistant Increaser Adapter Pipe Fitting for Vent System - Amazon.com
Reduced Duct Elbow
Air Duct Reducer 5" to 4", A-KARCK Round Duct Adapter Galvanized Steel for Inline Ventilation System, Connect Pipe with Duct Fan or Dryer Vent - Amazon.com