Do you look down when you walk? Head tilts to one side? Do you prefer a straight, forward look? If you wear glasses, it is easy to be aware of the glasses frame and its relationship to level. I use mine as a reference to check if my head is down and track my elevation to level. If my eyes want to look down or up or sideways, they can. But if I am seen from far down the hallway, I want a clean symmetric even look, and this is one thing I do.