The Klein Tools tester consists of two parts: a transmitter and a receiver. It works like this: you plug the transmitter into an outlet or light fixture, and scan the electrical panel with the receiver. The right dispenser is found quickly and accurately. When you find the correct dispenser, the receiver does not just light up, it gives a visual and audible signal. This device works with 90-120V AC networks. The transmitter has a built-in RCD tester, you can not only find the right machine, but also check the condition of the wiring and the operation of RCDs. The transmitter is conveniently inserted into the receiver, forming a compact kit. Everything is always at hand and nothing gets lost. Another nice thing is the universal compatibility. The transmitter has a triple plug that fits most grounded outlets.