If you're interested in this device, then you probably know what it does. It can hook up 8 MIDI Inputs and 8 MIDI Outputs to keyboards, FX devices, etc. Very useful in a live performance situation when you need to route one keyboard to another in a multi-keyboard setup, and also routing your keyboard to your external rack mount sound devices. It can also do program changes, and many other helpful things. If you have a lot of external MIDI gear in the studio, this is also helpful in interconnecting that gear and programming various routings and assignmnets.