Extech CB20 Circuit Breaker Finder (Discontinued by the Manufacturer) Quickly locate Circuit Breakers and Fuses Receptacle Tester (Transmitter): Test GFCI circuits, LED indication of 2 test conditions and 6 wiring faults, Test Reversed/Open Connections Complete with Receiver, Transmitter and 9V battery Microprocessor-based automatic sensitivity adjustment, Audible and visual indication, low battery indicator, Ergonomic design