A vehicle electrical circuit tester allows you to check voltage and ground in typical DC circuits. But its specialty is that it can apply voltage and ground to the circuit. In this way, the PB100 acts as a test lamp. This makes it possible to test components and circuits without using crocodiles and jumpers. Voltage or ground can be applied directly through the top of the unit. A front panel LED indicates the battery voltage when connected. The built-in 8-amp circuit breaker will protect the circuit from overload and overheating. Features a 20-foot cable for connection to the battery and easy access to the trailer connector on the back of the machine.