Kenton MIDI Thru 5

I use it to sync my synths through midi. Although MIDI din in general might not be the best solution for syncing synths as analogue clock is faster and much less (if no) jitter MIDI din is still a standard and cables are somewhat cheaper, this box does just that, great little solution for distributing MIDI to all devices.
p.s. After a while some ports stopped working, I though it was the cables but no, it was the port.