【CIRCUIT BREAKER】The PS100 Autel voltage tester is short-circuit protected. PS100 internal circuit breaker will trip if it becomes overloaded. Determine the positive, negative, and open circuit. 【AVOMETER】PS100 circuit tester can easy to read AVOmeter, so you can easily use your fingers to control PS100, simply read DC&AC voltage, current and resistance. 【FLASHLIGHT】 Built-in Flashlight enables you to work in the dark. Even in a dark environment where you can't see clearly, PS100 can give you a good view. 【LONG CABLE】The PS100 powerscan contain 20ft (extendable) cable provides excellent accessibility to test along the vehicle. 【POWER SWITCH】 With a flip of the power switch, you have an instant hot/ground lead for powering up electrical components like cooling fans, relays, etc.