It is the best electrical tester for reducing diagnostic time in automotive electrical systems. After a simple hook-up of the unit to the vehicle's battery, automotive technician can conduct a positive or negative battery current to the tip by rocking the rock switch forward or backward. The unit can be used to measure DC voltage and test for continuity or for bad ground contacts, It can also be used to follow and locate short circuits. It is short-circuit protected, its long cable allows you to perform test easily. The unit is powered by the vehicle battery directly.