Every Auto, Truck, Farm, Industrial, Marine Alternator has inside it what is called a Bridge Rectifier. The Bridge Rectifier is the assembly in every alternator that converts the AC (alternating current) that alternators make to DC (direct current) for use by the vehicles battery & electrical system. The Bridge Rectifier converts AC to DC using diodes which are semiconductors that are one way gates. Diodes allow current to flow in only one direction making alternating current into direct current. One very important note when it comes to high output alternators and bridge rectifiers. When you upgrade the output of your alternator you must also upgrade the diodes in the bridge rectifier to a higher amperage rating. Example: If you have a 100 amp alternator with a 110 amp rated bridge rectifier and then you upgrade the alternator to 200 amps but you still have the 110 amp rated bridge rectifier, it won't last long. We use Heavy Duty Single, Dual and Triple Internal and External Bridge Rectifiers to increase the durability and prevent High Output Alternator failure.