It can test most signal line combinations for XLR, 1/4", and two RCA (phono) jacks. It features an on/off switch with an LED indicator and four LEDs arranged in a straight row. When a signal cable is connected, if any of the PIN 1, 2, or 3 lights fails to illuminate, it indicates a problem with the corresponding wire. A red LED lighting up signifies reverse polarity in the cable, making it simple and practical. Its hands-free design allows you to move the signal cable being tested to locate intermittent fault points. This Tester signal cable tester includes an LED that indicates sufficient testing power, showing that the device's 9V alkaline battery has adequate power for testing.