This is the older serial port version. If you have the newer USB version, you can network them together for a total of 16 MIDI ports. The correct serial cable to network them is included.
Been stored in a closet for several years, but was working great last time I had it installed (networked to my USB MTPAV). I can show you how to network them if you need help, it's pretty easy.
Two of the knob fronts were missing when I bought this. I found some screw covers at the hardware store to cover that. If you look closely you can tell. One of the little bolts is missing in the back - I never noticed that until now - if I make it to the hardware store before this sells, I'll replace it.