This instrument is used to identify and trace wires or cables without damaging the insulation. It can also be used to test for short circuits and locate open circuits. It can also be used to identify specific phone line conditions to simplify phone line installation, debugging, and maintenance. The instrument includes a transmitter and a receiverProvide an adjustable volume controlCompatible with all common tracking audio sourcesUse RJ-11 sockets, jumpers, or alligator clips for easy wired connectionCheck the continuity of cables or wiresTrace cables or wires and diagnose breakpointsIdentify the status on the work phone lineTransmit single or alternate audio over cables or wires and use audio probes to receive signalsAdjustable audio on sound probesIncluding RJ11 socket for telephone and clip for cablesDurable design for many years, trouble-free useBattery: 2 * 9V battery (without battery)Color yellowMaterial: ABSSize: 255 x 120 x 36 mmPackage contents:1 * cable transmitter1 * cable receiverOnly 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.