Features: This tester is for testing the continuity of Ethernet LAN cables and fixed phone wires. Test RJ45, RJ11 telephone cables and network cables and detect POE quickly. Used for testing your homemade Ethernet patch cables to make sure they are in working order prior to connecting your devices. LED light for your clear sight, directly and correctly. Slow and fast test switch function, for your different needs. Compact design specifically tailored for system integrators and installers. This tester needs a DC 9V battery for power supplying, which is not included.