ESR840 is a high quality regulator/rectifier that replaces the OEM regulator on Kawasaki ZX-9R models between 1998 and 1999. Our ESR840 offers superior performance by utilizing our latest generation of power circuit which is installed in a highly efficient heat sink. ESR840 offers a super stable battery voltage across the RPM range and will run much cooler than the OEM unit due to the improved heat sink design. All in all: a large improvement over the not-so-reliable stock unit. Like all regulator/rectifiers manufactured by ElectroSport: ESR840 comes with a full one year warranty.