Ventilation Type Flexible Siliocne Duct Connector with Flange - China Easy to Operate Flexible Duct Connector, Reinforced Fiberglass Fabric Connectors | Made-in-China.com
Mounting Flange for Ventilation Blade – Manncorp Inc.
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
Active Ventilation 8 in. Dia. Aluminum Round Back Roof Vent with Curb Mount Flange in Mill Finish RBV-8-C2-CMF - The Home Depot