With the Metropolix Backpack you connect the Intellijel Metropolix sequencer to the USB/MIDI ports of the Intellijel 4U and 7U cases in the simplest possible way. The small circuit board is simply plugged onto the module, screwed tight and connected with the short cable. The sequencer can be freely positioned in the Case using the longer ribbon cables supplied. This is ideal for anyone who primarily wants to synchronize the Metropolix with other equipment in a MIDI network. The Palette 62 Case only provides MIDI In, while the Palette 104 and 7U Performance Case offer MIDI In and Out. Backpack makes the USB Extender 1U/3U superfluous, unfortunately the possibility of connecting the Gx Expander is then lost.