The Field Guardian Digital Fault Finder is a digital volt meter, fault finder and joule meter all in one. It includes three probes to allow multiple testing profiles. The ground probe, attached to the unit by wire, is inserted into the ground, or placed in contact with a ground wire, when testing for fence voltage and energizer output. The exposed brass probe that extends from the top of the tester is used when testing fence voltage and energizer output. The partially-enclosed probe, accessed from the front of the tester, is used during fault detection. The 200 ohm resister (Part No 660085) is required to to test joules.

It can test voltage of chargers up to 15,000 volts which is more than the majority of all other testers on the market. You also see very few joule meters in the USA that can tell you what the true output joules are of your charger.