Locates the correct circuit breaker or fuse without turning off the power. Simply plug the transmitter into an outlet and trace for the correct breaker at the electrical box. Transmitter also verifies wiring and tests GFCI operation. Bright red and green LEDs indicate if receptacle is correctly wired or will indicate which of the 5 fault conditions exists. Convenient storage position for transmitter/receptacle tester. Complete with Receiver, GFCI Transmitter, and 9V battery.