So this is really a bit cheeky. I didn't feel I could really separate out the PO series although I do appreciate that a lot of people won't have the full set. So I'm calling this devices 2, 3 and 4 in one go, and let's face it. They're pretty cool.
So, to celebrate them, here are some videos on them in action.
Sync is difficult though, I've heard quite a few people struggle with all three, although fitting two together seems to be more common.
You could even try picking them up cheap on eBay ...
PO Series on eBay