The TG20 Wire Tracer Kit detects wire pairs, checks their continuity and the polarity of the telephone line. The transmitter has output cables that terminate in a modular RJ11 telephone plug. The non-contact amplifier probe audibly identifies the selected wire or cable, allowing you to easily trace the connection from source to terminal. Includes wire tracer probe and transmitter with RJ11 phone plug, a pair of alligator clips and two 9V batteries.