If you are current Electroscopes Model 20 or Model 301 owner and want to increase the performance of your Electroscope, then a upgrade may be for you. The Model 20 and Model 301upgrades include a Seeker accessory which will improve detection off the antenna and increase discrimination. The upgrade also includes replacement of any defective switches and the inclusion of our latest electronic circuitry. The upgrade allows the Electroscope to be compatible with any current accessory which may not be possible on some older models.