ESR635 is a high quality regulator/rectifier that replaces the OEM regulator on the Yamaha YFM 350 Warrior models between 2002 and 2004, as well as the YFM 350 Wolverine from 2002 thru 2005. We incorporated our latest generation power circuit inside our very efficient heat sink design resulting in our ESR635 which is superior to the Yamaha OEM unit on these ATVs Our ESR635 offers a superbly stable output voltage which means your battery will get the optimum charge at any engine RPM. And thanks to our advanced circuit and heat sink this regulator runs much cooler than the stock unit. ESR635 is a Plug-In replacement regulator/rectifier that comes with a full one year warranty.