eBay and Craigslist finds

This. A fixed wheel hub adapter that you screw onto a road hub and is double threaded for a cog and lockring. So you lock the lockring to an adapter that isn't, er, 'locked' itself? Am I missing something or is this as stupid as it seems?

Yeah a weird one. At first I thought, ah ha, its like some kind of adapter to put a screw on cog onto a cassette hub, but then, where the logic in that, other than it makes a larger contact patch with the freehub.
Then I thought, maybe its for screw on hubs, but he's invented an amazing way of attaching it so that screw on cogs can be used, but no. All it does is just provide a chainline re-space? Guess its useful to about 15people maybe.