The TG20 Wire Tracer Kit identifies wire pairs, check continuity and test telephone line polarity. Transmitter has output cables terminated in modular RJ11 phone connector. The non-contact amplifier probe audibly identifies the selected wire or cable so that you can easily trace from source to termination. Comes complete with Wire Tracer Probe and Transmitter with RJ11 phone connector, a pair of alligator clips and two 9V batteries.