The flykantech.com THRU-IV MIDI THRU BOX is a 4 in 4 out MIDI Thru Metal Box (5 Modes - 4i/4o, 1i/4o - Input A/B/C/D 4O ) takes the signal coming from a single MIDI source and split it into a number of identical copies. The Input takes a MIDI signal, buffers it, and sends it out to the 4 Outputs. MIDI THRU BOXs are useful for all sorts of applications, wherever you need to send the same MIDI signal to multiple locations, for example in a payback rack, or maybe linking multiple synth modules to the same controller. There are loads of MIDI thus on the market but THE MIDI THRU BOX has a trick up its sleeve. The USB Port does not pass data and is for power only.