The REED R5500 is a 3-in-1 electrical tool that combines a circuit breaker finder, a receptacle wiring tester, and a GFCI tester in one kit. Plug the compact transmitter into any outlet, then sweep the included receiver/finder across your breaker panel to instantly locate the matching circuit via its adjustable-sensitivity indicator, while the transmitter itself reads out common wiring faults and lets you trigger a GFCI trip test. A practical time-saver for electricians working on live panels without needing to shut off power first.