Check the listing for details. Optical fiber network tester network cable finder anti-interference line checker. Color: yellow, Condition: New. Listed at 20.20 USD. Multifunctional telephone line finderRefuse to damage the insulationIdentify / track wiresTest the RJ11 telephone line for continuityIdentify phone line statusFunction introduction:1. It can receive audio signals on cables / wires;2. Check the connection and disconnection of cables or wires;3. Single audio and double alternating audio can be sent to the cable / conductor;4. Accurately track the breakpoint position without damaging the insulation layer;5. Identify three phone line states (idle, busy, ringing).(PS: do not connect to any active circuit in this mode.)Product precautions:1. If the cable tracker is not used, set the switch to "off".2. If the cable tracker is not used for a long time, take out all batteries.3. Keep away from moisture.4. Do not use cable tracker in high voltage environment.5. Always follow this user manual. Otherwise, it may cause damage to the test instrument or personal injury to operators.Quantity: 1pcs