Most Of The People Are Covering Their Windows And Doors With Mosqito Nets But Nobody Care About Wall Air Holes Chimney Vent Pipe Holes And Exhast Fan Holes.These Holes Are Given A Way To Enter Mosquitos and other Insects And They Spread Corona Like Diseases In Our Family .Myy Brand Exhaust Fan Cover Or Chimney Cover with Dust controller for Six inch air holes are high quality plastic nets with dust controllers integrated into them to prevent mosquitoes,lizard,cockroach,bee,spider and rat from entering while ensuring air passage. For years, home owners have been using different products that are difficult to fix, maintain or gets clogged with dust in a few months and render themselves useless but this is very easy to fix and clean,fixing with gum or double sided tape is not recommended.we would suggest you to fix it using screw to the wall