Mates with NEXUS Series TP-120 plugs and plugs TP-101 and TP-102. A Fifth contact has been added to the TJ-120 design in a normally open circuit with the No. 1 contact to make the TJG-120. Insertion of a four conductor plug closes the No. 1-5 contact circuit. The TJS-120 is the same as TJG-120 except the fifth, or swithching contact is normally in a closed circuit with the No. 1 contact. Insertion of a four conductor plug opens the No. 11-5 contact circuit.