Features: This instrument is a multi-functional handheld cable testing tool. It has wide application with reinforced cable types and multiple functions. It is a necessary testing tool for telecommunication engineering, wiring engineering and network maintenance person. Work profect when RJ11 RJ45 cable is on power Wire Tracing: Trace RJ11, RJ45, cables or other metal wire (via adapter). Easy and fast to locate the breakpoint without opening the wires cover. Network cable collation: Judge short-circuit, breaking circuit, open circuit and crossing. Description: Test line level, positive and negative polarity. Status of telephone line checking: Test the working status of telephone line (idle, ringing, and off-hook) and judge TIP and RING line. Check wire continuity. Specifications: Operating temperature: 0 C ~ 40 C, maximal 80% relative humidity (non-condensing) Storage temperature: -10~50C, maximal 80% relative humidity (non-condensing, battery not included) Altitude: