PROFESSIONAL WIRE TRACKER - The line finder can quickly find the required line pairs among numerous ones. It's adaptable to RJ45 terminal & RJ11 terminal and other metal wire in low electricity. Please note that it can not be used to track wires with high electricity (max currents:10mA- 30mA, and max voltage is 10V ). Besides, You need to prepare two 9V batteries yourself. VERIFY LAN CABLE CONDITON - Plug one side of the cable into the emitter and the other side into the receiver, it can trace cable assignment and cable state (2-wire), also can be used test physical connection status of network cable, such as open circuit, short connection, miswire and reverse connection. It can take place of cable tester. TELEPHONE LINE TEST - We only need the emitter to test the status of working of telephone lines, such as judging TIP or PING line and judging whether the telephone line is idle, ringing or off-hook. Rapidly find the target wire from among plenty of telephone wires, network wires, and all types of connected operating Ethernet switch /Router/PC.