They can be used in installation of network cables including RJ-45 EIA 568A/568B (AT&T 258A) 10 Base-T, token ring, RJ-11/12 USPC and coaxial BNC cable. They can also test continuity in RJ-45, RJ-11, and BNC cables. The cable testers comprised one base unit and one remote unit. Automatically runs all tests and checks for continuity, open, shorted and crossed wire pairs. Requires a 9V battery.