ACDelco GM Original Equipment A/C Drive Belt Tensioners keep the proper amount of tension on the drive belt by pushing the drive belt tensioner pulley against the belt. The tensioner may be manually or automatically tensioned depending on application. Drive belt tensioners are part of the accessory drive belt system. This original equipment A/C drive belt tensioner is a GM-recommended replacement for your vehicle's original component and has been manufactured to fit your GM vehicle, providing the same performance, durability, and service life you expect from General Motors.