These are the tracks that guide your door from the closed to open position, and back to closed again. The door rollers are attached to the door and move freely and smoothly through these tracks. If one of your door tracks becomes damaged in any way, your overhead door will loose its smooth operating process if it even opens at all. When you make your garage door opener work harder, you drastically shorten its life. In extreme cases of door track damage, the entire overhead door can dislodge itself from the tracks and fall on to whatever is unfortunate enough to be under it (hopefully, NOT YOU!).