This single channel passive video balun also has a built in ground loop isolator. The ground loop isolator is used to prevent distortion in CCTV video transmission over CAT5 cable. Distortion can be caused by other power lines, other electronic devices on the same circuit and differences in grounding. These units are designed to be installed on the end of the cable before connecting to the security camera. You will need a video balun for the other end of the cable as well, but it does not need to have a built in ground loop isolator on that end.