Your rearview mirror glues to the windshield to allow you to see vehicles directly behind you. The rearview mirror may be secured to a button attached to your windshield with glue. If the glue wears out and the button falls off, your mirror may be damaged. Cracks in the rearview mirror or a mirror that won't support itself when positioned may be reason enough to consider a replacement. If your rearview mirror creates any problems that keep you from seeing behind and around your vehicle, it should be replaced for your safety. O'Reilly Auto Parts carries universal rearview mirrors and buttons for your repairs. Side view mirrors are also available to assure your safety on the road.