This Cable Tracker is designed to identify and trace wires or cables within a group without damaging the insulation. For telephone line, it can identify some states in the line. With this instrument install, debug, and maintain telephone line is more convenient. A Sender and Receiver is included in the Cable Tracker. Color: yellow Material: ABS+ metal Application: Testing polarity of phone lines Tracing a wire Finding wires buried behind drywall Test whether a cable is interrupted Find interrupts in cable Compatible with all common tracing tone sources Judge continuity of the cables or wires Track the cables or wires, and diagnose the break point. Receive the tone signal on the cables or wires (telephone line) Identify the state in the working telephone line (clear, ring, busy) Send a single solid tone or dual alternating tone to the object cables or wires Receiver: On/Off button Test button 3.5 mm earphone jack Sender: Tone/Off/Cont (Continuity) switch Tone/Cont (Continuity) LEDs Red and black test leads cable (61cm length, approximate) Built-in RJ-11 telephone cable (47cm length, approximate) Receiver Dimensions: 23 x 4 x 2.3cm (H x W x D, approximate) Sender Dimensions: 6.5 x 5.6 x 2.1cm (H x W x D, approximate) Power : 9V battery (6F22) Not included Package Contents: 2 x Cable Tracker Sender 2 x Cable Tracker Receiver 2 x Carrying Pouch 2 x English User Manual Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.