I use it to be able to connect an electric guitar to a microphone input on a mixer, for connection to the line in of the Behringer UCA222. It is very convenient, it also has a ground lift which is needed in some cases and solves the known problems with ground loops. It has a very good and sturdy construction, it has several connections, it is just for mono sound, not stereo. If we want stereo, we need two of these. It could be used for ground loops, which I tried and it eliminates them. For that, we need the Behringer Hum Destroyer, which is stereo, cheaper, and does not require power, while this one requires a 9V battery to work.