ESR is a high quality regulator/rectifier which replaces the OEM regulator. It uses the latest developments in regulator circuit design and incorporates a very efficient heat sink which dissipates the generated heat quickly. Built with only the highest quality components for the internal power circuits and the result is a regulator/rectifier that is superior to the OEM part. Offers advanced circuits offer a stable output voltage across the RPM range to charge the battery. Plug and play for most V7 and Cal 1100 models.