This tester is designed to handle twisted pair, straight, and Cat5/Cat5e/Cat6/UTP cables with RJ-11 or RJ-45 connectors to test for breaks or signal loss in your internet or LAN connection. Easy-to-read LED indicator lights to alert you to possible gaps in your signal transfer through each line. Cable Tester for RJ12, RJ11, RJ45, Cat 5e, Cat 5, Cat 6, 10/100 Base-T, AT&T 258 A, TIA-568A/568B etc. Test correspondingly double-twisted cables 1, 2, 3, 4, 5, 6, 7, 8 and Ground. 9 LED lights to indicated wiring connection on both remote and master unit Grounding Test. Easy read LED display which indicates problems. Power: 9V battery (Battery not Included) Keep your network running smoothly by testing wrong connection, short circuit and open circuit