4 Inch Stainless Steel Dryer Vent Cover Diameter ?:4 Inch The flap automatically opens when

The flap automatically opens when excessive lint/dust accumulates

blocking it

for connecting two ducting of different diameters or for connecting hose to inline fan/exhaust vent

typically after the safety baffle air vent is blown open

4 Inch Stainless Steel Dryer Vent Cover Diameter ?:4 Inch The flap automatically opens whenFeatured SUS 304 stainless steel material; Strong Anti corrosion,non toxic. Fly screen mesh effectively prevents anti insect from entering. U shape with drainage channels special design,waterproof and rain resist. Light paint surface to resist rain, anti dust and rusty,more durable. Buckle installation make a better connection between the ventilation and wall.