These cable testers are a stand-alone test device. They are designed to test popular PC data cables, printer, monitor, modem, mouse extension, game, BNC coax, RJ45, 1394, and USB cables by identifying the wire connection status: open, short, cross, miswire, and continuity of wires and pin configuration. It is a very good tool for most cable dealers, cable assembly house or system integrator to quickly check the pin configuration or troubleshooting in every work environment.