【Backdraft Prevention Damper】Dimensions: Φ:150MM, New Model: Hardness Enhanced, Material: Galvanized Steel. 【Application & Principle】Application: Backdraft prevention. Flow Direction: Unidirectional. Operating Principle: Wind. The check damper opens with exhaust airflow and closes when outside air enters due to wind, etc. 【Installation Method & Backdraft Prevention】Installation Method: Install the shaft of the backflow prevention valve vertically towards the ground. This product uses galvanized steel, making it durable and lightweight. It automatically opens and closes with exhaust airflow, allowing dirty air from the room to be expelled outside the building and preventing the entry of outside dust and insects. 【Low Noise & Airtightness】By attaching a sponge strip to the air outlet of the backdraft prevention damper, the noise from automatic opening and closing due to exhaust is significantly reduced. The unidirectional flow, robust damper blades, and sponge strip design also improve internal sealing performance. 【Connection Method & Wide Range of Applications】Recommended connection method: Backdraft prevention damper + fixing hose band + exhaust duct hose. The backdraft prevention damper is ideal for DIY ventilation systems. It is widely used in scenes such as household range hoods, pet toilet ventilation, agricultural greenhouse cultivation, clothes dryers, and industrial factory exhaust. Okryain Backdraft Prevention Damper, Hardness Enhanced, Check Damper, Check Valve, Backflow Prevention Valve, Unidirectional Dustproof Ventilation, Ventilation Outlet, Ventilation System Airflow Control, Stainless Steel, Backflow Shutter, For Ventilation Fan Duct Connection (6inch/150mm)