This set of tools can be used for all kinds of cable line installation, inspection and maintenance, and can judge the work of the telephone line in various states, more convenient for the telephone line installation, debugging and maintenance work. It allows you avoids damaging the insulation of the cable. Features: Judge continuty of the cable or wires. Track the cables or wires, and diagnose the break point. Receiver the tone signal on the cables or wires (telephone line). Indentify the state in the working telephone line (clear, ring, busy). Send a single slid tone solid tone or a dual alternating tone to the object cables or wires. Tail large speakers, sound loud, in a noisy environment can also be heard. Inteligence button and indicator light. 3000m effective detection distance. Easy and convenient to use. Specifications: Send tone frequency: 1.5kHz Receive frequency range: 100Hz-300kHz Power supply: 6F22, 9V (not included) Receiver size: 238 * 43 * 26mm / 9.4 * 1.7 * 1.0in Emitter size: 145 * 35 * 25mm / 5.7 * 1.4 * 1.0in Receiver weight: 56g / 2.0ounce Emitter weight: 64g / 2.3ounce Shell color: green Package size: 300 * 130 * 60mm / 11.8 * 5.1 * 2.4in Package weight: 200g / 7.1ounce Package list: 1 * Emitter 1 * Receiver 1 * Users Manual