A mouse can squeeze through a hole the diameter of a ballpoint pen. The relatively soft bones of the skull, tiny body and great teeth allow mice to squeeze through incredibly small holes.
There is no gap a little more than 6 mm in diameter threatens your home disaster — you’ll definitely find a mouse that, gnawing everything in its path and deftly squeezing through any obstacles, settle you, with your numerous family, friends and fans and will live happily ever after at least until next spring.
Therefore, the best way to protect yourself from them is quite simple, although it requires some effort: close all the cracks in the house. However, keep in mind that mice are excellent athletes: they can jump up to 46 cm vertically, they can swim, they can crawl up in the abdomen, climb walls and much more.