TerraBloom Inline Duct Fan 100 CFM, 4 Inch, HVAC Metal Booster Blower For Exhaust and Intake Through 4" Ducting
iPower 4 Inch 8 Feet Air Ducting Dryer Vent Hose for HVAC Ventilation, 2 Clamps included
Fantech 9800000 RSK-4 Backdraft Damper, 4" Duct