Key Features: "Ideal LAN cable tester while building or troubleshooting networks. 9 LED lights to indicated wiring connection on both remote and master unit Grounding Test. It can judge wrong connection, short circuit, and open circuit., It can quickly & easily check following the type of cables: RJ12, RJ11, RJ45, Cat 5e, Cat 5, Cat 6, 10100 Base-T, AT&T 258 A, TIA-568A568B, etc., It can test correspondingly double-twisted cables 1, 2, 3, 4, 5, 6, 7, 8 and G, Operates from a single 9V PP3 battery"