Kair Round Connector 100mm - 4 inch to Connect Duct Pipe or Flexible Ducting Hose

4 Inch Flexible and Rigid Ducting

Vent Systems 100 mm / 4" Inch Round Male Duct Connector – ABS Plastic HVAC Inline Ducting Fittings for PVC Flexible or Rigid Vent Hose Pipe – Dryer Air Ventilation System Tube Adapter