The single VGLI (Video Ground Loop Isolator) balun is a high performance connector that eliminates ground loop problems. It can prevent picture tearing, cross talk and rolling and other interference caused by power cables laid by others. This equipment is designed to be installed on the end of the cable before connecting to the security camera. Use of this requires that you install a video balun on the other end of the cable but you will not need one with built in ground loop isolator on that end.