ESR640 is a modern high quality regulator/rectifier that is a plug in replacement for the stock Honda regulator. We incorporated the latest generation of our Power Circuit and built it inside our efficient heat sink unit. ESR640 offers superior performance compared to the OEM unit. Voltage regulation is stable and the advanced heat sink ensures that our ESR640 runs much cooler than the stock regulator/rectifier. ElectroSport offers ESR640 with a full one year warranty.