Features: Quick&Easy Diagnostic: With this tool, you can judge the cable and wires continuity easily, and diagnose the break point or check the cable short easily. This tool can receive the tone signal on the telephone line, and identify the state of the working telephone line(clear, ringing, busy). Probe Design: The receiver probe is made of curved wire and insulating silica-gel to enable it to detect cables in crowded and difficult environments. According to the characteristics and sensitivity of the circuit, the probe can pick up the signal of cable within a certain ranges, but it is better to place the receiver's probe above or below the cable vertically. Short&Break Circuit Checking: This tool can be used to check the short and break circuits, and also can help you to find and identify the cable. Storage Bag: Comes with a storage bag for you to neatly store the tools in the bag, easy to carry and not easy to lose. The MY6813 type is without LED light, and the MY6814 type has a LED light on the receiver probe. Specifications: Material: ABS Type: MY6813, MY6814 (optional) Max. voltage: direct current 42V Tone generator output(square waveform): singles 1500Hz or dual 1300~1500Hz Send tone frequency: 1.5kHz Receive frequency: 100Hz~300Hz Power: 2 * 9V 6F22 batteries (NOT INCLUDED)