Get your vehicle Ready for the Road Ahead with a stable source of power for all of its electric accessories, with the Prestolite 12V 90A Spool Mount Alternator. With the help of the serpentine belt, this replacement alternator converts the mechanical energy from the engine into a usable current of electricity, which is then stored in the battery. Manufactured with rigorously tested wiring to keep your power steering, headlights, radio, and more operating at their best. FleetPride is your First Click in Heavy Duty .