The screen does not stop mice, they come in from the fin area.
If the equipment is used frequently, like mowing or snow duty, they don't have much of a chance building a reproduction home.
If you are paranoid of the little cuddly creatures, a pair of snap traps baited with peanut butter in close proximity, will keep things in check.
(Hint:
they crawl up the tires)
The rotating screen helps keep grass, leaves and other debris from packing the cooling areas.
Happy trapping.
