Astrotek RJ45 RJ11 Coaxial Network Ethernet LAN Phone Cable Tester Wire Tracker The ASTROTEK Cable Tester for RJ12, RJ11, RJ45, Cat 5e, Cat 5, 10/100 Base-T, AT&T 258 A, TIA-568A/568B .etc, Capable to judge wrong connection, short circuit and open circuit.Test correspondingly double-twisted cables 1, 2, 3, 4, 5, 6, 7, 8 and Ground • easily clarify cable, continuity, open and short • 9 LED lights to indicated wiring connection on both remote and master unit • Grounding Test • Provides flexibility for cable management with a neat and clean appearance • Power: 9V battery ( Not Included )