RJM MultiBox MIDI Splitter

The MultiBox is designed to be a multi-purpose problem solver in MIDI systems. It can be used for any of these purposes, most of them at the same time:

MIDI Thru Box – splits one incoming MIDI signal to multiple outputs (up to three standard 5-pin MIDI outputs)
TRS MIDI Converter – converts standard 5-pin MIDI to TRS MIDI for use with devices that require it
Phantom Power Adapter – combines a 5-pin MIDI connection with AC or DC power and routes them to a 7-pin MIDI connection. This can be used to phantom power a compatible MIDI controller
Bidirectional MIDI Converter – splits a bidirectional MIDI connection into separate MIDI input and output jacks, or combines a MIDI input and output connection into a bidirectional MIDI connection
Typical Uses

Use as a MIDI splitter (AKA thru box) to split the output of a MIDI controller to multiple devices, both standard 5-pin MIDI and TRS MIDI.
Put in a rack with an Axe-Fx or Kemper Profiler, and it will combine MIDI In, MIDI Out and power connections into a single 7-pin MIDI cable to go to the MIDI controller.
Split the bidirectional MIDI connection from a Mastermind into a MIDI input and multiple MIDI outputs.