Installed as an air inlet or outlet, the exhaust hood must cover the ventilation system to prevent rodents and insects from entering the house. This wall inlet has a grille guard and can rotate the knob to adjust the air flow. Adjustable panel, you can adjust the air flow by turning the knob.The panel can be completely closed. The black sleeve is detachable, easy to clean and maintain.Wall or ceiling mounted, perfect for bathroom, office, room exhaust and ventilation use. Ideal for all dryer vent pipes/pipes, bathroom ventilation openings and slide-outs, air conditioning systems, kitchen fans and slide-outs, all household wall ventilation openings, heat transfer and ventilation systems, extractor hoods and a variety of other devices for industrial applications. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.