" Product Description: This set of tools can be used for installation, inspection and maintenance of various cable lines, and for telephone lines it can judge different states of phone lines at work, which is more convenient Installation, commissioning and maintenance of telephone lines. When it works, you don't need to damage the insulation layer of the cable. This tool set includes one transmitter (MS6812-T transmitter) and one receiver (MS6812-R receiver) each Features: Determine if the cable line is continuous Draw the cable line and identify the location of the line break Receive signal in cable line (telephone line) Determine the state of the working telephone line (free, ringing, off hook) Send single-tone or dual-tone signal to target cable line technical parameter: Beep: 1.5 kHz Receiving frequency range: 100 HZ-300 kHZ Battery power: 9V (6F22) 1 Size: receive end 238 43 26 mm transmit end 145 35 25 Weight: 106g at the receiving end (including battery) and 114g at the transmitting end (including battery) "