The KritterCap Corner Insert is a patented product that can permanently stop attic mice at the door. Designed to fit 2.75-, 3-, 3.5- and 4-in. corner posts, the cap fits up inside the corner post within minutes and does not require any screws, caulk, foam or glue to hold it in place. When properly installed, it will not fall out, nor will it deteriorate over time. It lets the corner post breathe so there is no chance of rotting the sill plate, due to condensation, and causing an infestation of carpenter ants. It prevents chipmunks from hiding from dogs and predators that chase them into the corner post. It can even help prevent cold winter drafts in the corner of the home.