The 1x4x2 Thru box is an output expander for the Swynx, and can also act as a standalone MIDI and DIN Sync Thru box.
The Thru box allows you to pass both MIDI and DIN Sync data to four seperate devices simultaneously. MIDI Thru boxes are quite common, but 1x4x2 is the first to provide DIN Thru capabilities.
Power is provided via MIDI.