SUITABLE compatibleThis tool set can be used compatible all kinds of cable line installation, inspection and maintenance, and can assess the work of the telephone line in different states. It will prevent the cable insulation from being damaged. PRACTICALEstablish the continuity of the cable or wires. Trace the cables or wires and diagnose the breakpoint. MULTIFUNCTION Receive a tone signal over cables or wires (telephone line). Identify the working phone line status (release, ringing, busy). Sends single sliding tone or double tone on the cables or wires of the object. HUMANIZED DESIGN Large rear speakers, loud sound, can also be heard in a noisy environment. Intelligence button and indicator light. 3000m effective detection distance. EASY TO USE Not only rich in functions, this cable finder is also very easy to use and will be of great help to you.