The Imp-THRU splits the MIDI signal to four high speed MIDI Thrus. This is particularly useful, if more than one Imp-3PDT or Imp-SPST is to be in one effects device. The latency is less than 1µs.
But it is not limited to Imps. You can build your own MIDI Thru box with it.
More information at https://oscillatordevices.com/imp