How’s the fit? These say 5/8 but I have also been told in this thread that 1/2 is correct.I bought these plugs on Amazon. A little over $7 for 30 of them. I installed about half. The air definitely hits the sides better and still gets the center too. Haven’t tested yet but it can’t be worse than it was last week. I’ll play around with the amount I use and the location of the plugs next time we have a snow storm.