The handheld cable tester has several Features such as compact, lightweight, high accuracy, easy operation, built-in LED lamp, earphone jack, and wide applications like wire tracing, network and telephone line test, line detection and alignment, line level or positive and negative polarity detection, wire continuous detection, etc. It is an essential test tool for people who work for telecommunication engineering, wiring engineering, and network maintenance. Features: Wire Tracing Function: quickly find the required line among numerous cables. the instrument is suitable for RJ45 interface cable, RJ11 interface telephone line, and other metal wires. Line Detection & Alignment: for completely testing and detecting the line sequence, the physical connection of the open circuit, short circuit, wrong and reverse connection of the network cable. Telephone Line Status Detection: use the transmitter to test the status of the working telephone line (idle, ringing, off-hook) and discriminate TIP or RING line. Simple & Fast: when searching for cable lines, it is not necessary to strip the line skip, and can determine the position of the line breakpoint. Multifunctional Cable Line Finder: also has functions of line level or positive and negative polarity detection, wire continuous (passage) detection. Earphone & Flashlight: equipped with a pair of earphone for helping wire tracing in the noisy place. Both the transmitter and the receiver designed with a LED lamp for auxiliary lighting in the dark area. Comes with a black bag for storage and conveniently carrying around, really an essential test tool for people who work for telecommunication engineering, wiring engineering, and network maintenance. Specifications: Material: ABS Signal Transmission Distance: Approx. 300m Power Supply: 1 * 9F 6F22 battery(transmitter), 1 * 9F 6F22 battery(receiver) (both NOT included) Operating Environment: 0~40, 80%RH(non-condensing) Storage Environment: -10~50, 80%RH(non-condensing, no battery) Altitude: