The MIDI Solutions Thru Box is a simple box that allows you to send a single MIDI signal to two separate outputs. It makes it simple to send a MIDI signal to two separate locations, and makes sure that your signal won't be degraded in any way. There aren't any other connections beyond the single MIDI input jack and the two MIDI output jacks, and doesn't need any extra power as it is MIDI powered and will turn on once you've made the connections. I've only used the Thru box in the recording studio, and I'm not sure that I can think of any other uses for the box beyond this.
It really couldn't be any simpler to set up and use the MIDI Solutions Thru Box. Simply make the connections and you're good to go! You can of course use this box with other MIDI Solutions boxes, which is what I'm sure many professional studios will be doing. However, you can use it on it's own if you don't need anything else. The MIDI Solutions Thru box isn't something that I've used on too many sessions, but we had it on hand in one of the studios that I've worked at, as it is something that was needed and came in handy more times than you would think.
If you're looking for MIDI boxes to make any sort of irregular (or regular) MIDI connections, MIDI Solutions is the company you want to be in touch with. They make reliable products that in many cases are unique and are hard to find elsewhere. While I'm sure you could find another MIDI thru box like this one out there, I haven't ever used another one, so I don't really have anything to compare this one to. I'd encourage you to do the proper research, but you definitely cannot go wrong with this box and with MIDI Solutions in general. The price is about right for something like this, as I don't think that it is over or under priced. I'd definitely recommend the MIDI Solutions Thru box for anyone in need of one.