Vent Systems 8" Inch Backdraft Damper - Backflow Shutter - Heavy-Duty Inline Springs Loaded - One-Way Airflow Ducting Insert - Inline Fan Vent Deflector

Vent Systems - 8 Inch Backdraft Damper - One-Way Airflow - Inline Fan Vent Deflector

EesTeck 4Pcs 8" Adjustable 304 Stainless Steel Duct Clamps Hose Clamp Pipe Clamp Air Ducting Clamp worm drive hose clamps (194mm-216mm)

Hon&Guan 8'' Soffit Vent Cover, Round Vent for Bathroom & Home (200mm)