In winter I use the 3/4inch, ya know the standard wood piece sold by all bee supply businesses. The board has two options: 3/4 inch and 4 inch. One simply rotates the board for the desired opening. I don?t have a mouse problem in Arkansas, they are few and far between,,,,, many chicken snakes, cats, foxes, even these huge lizards, etc keep the mouse population down.
In Lewistown, Montana, grain country, the mice were everywhere. Never seen so many mice. Place a piece of plywood anywhere in the alfalfa and overnight there would be a mouse den/nest built. Contrary to Arkansas where I have seen one mouse the past 9 years. So I don?t place mouse guards on my hives,,,, hives strapped for bear, all year, definitely!!!
Van