With both a transmitter and receiving unit included, the Extech TG20 wire tracer kit includes everything you'll need for sourcing a wire or cable from its source to termination.
How does it work? Simple - use the transmitter to inject a traceable signal into a cable, then use the included non-contact probe receiver to follow the cable along. The receiver will emit a steady tone as the signal is detected, allowing you to accurately determine cable direction.
For added precision, the system has adjustable sensitivity, ensuring that you don't detect false signals and instead trace exactly what you're looking for. The included transmitter can also be used to check telephone lines and for performing continuity checks (with visible indication).