Serpentine belts regulate multiple mechanical functions that are critical to your vehicle's operation.  Replacing these belts when they are showing signs of wear and tear will keep you on the road.

Just about every late model car and truck use a serpentine drive belt. It is a single ribbed belt that drives all the accessories, A/C, Power Steering, alternator and various other pumps and accessories. They don't last forever and they do need to be inspected often to keep you from getting stuck. Checking ribbed drive belts at every oil change insure you catch a bad belt long before it snaps.