I am looking at various vent covers for my house. I have a 3" Plumbing vent stack and a 4" Radon vent stack. The radon system is passive, which means I do rely on a chimney effect along with the fact that a breeze creates a draft tunnel down to the basement. I want to prevent the possibility of a squirrel or bird from a.) entering the vent pipes and b.) dying in the vent pipes after a quick trip to the bottom.
Doing a lot of reading it turns out this is a very technical topic! So far I see things priced from $5 to $40! Right now I am really leaning towards these simple little things because it prevents the issue at bay and appears that the slits would allow the continuation of passive venting.
I don't know enough to decide if these are the proper vent covers or not for my situation. I think the 3" stack would be okay, but I am concerned about the 4" radon pipe.