1. Easy to Diagnose: Circuit Tester with Light circuit probe is an electrical tester designed to reduce diagnostic time for automotive electrical systems. Comes with a 4m cable for easy testing. Along with large size alligator clip for easy onehand operation, will definitely improve your working efficiency 2. Multi Uses: Circuit Tester with Light Circuit detector can test for continuity, test for polarity, test for bad ground contacts, check switches, relays and the on off of diodes, fuses and circuits, track and locate short circuits. Making it an essential tool in your daily electrical troubleshooting 3. Safety Tools: Circuit Tester with Light Automotive test probe is the useful tool to determine if power is present and also as a means of safely powering up fans, motors and electrical circuits. Practical and convenient in use 4. Quick Identification: Circuit Tester with Light help you quickly identify the positive and negative polarity, when the probe touches the positive , the red light is on, and when the probe touches the negative , the green light is on.