I seen this ad in an old Dartsworld magazine from 1981:
[You must be registered and logged in to see this image.]I thought, that sounds interesting, then I found a colour ad of the same:
[You must be registered and logged in to see this image.]WOW! I would love to get some of those I thought.
I figured it was just a small independent company at the time so I doubted that I would ever get a set.
Amazingly I now have 2 sets!
And here they are:
[You must be registered and logged in to see this image.]They have a tungsten barrel. The interchangeable sleeves appear to be made of aluminium and just slide over the barrel and then are tightened on by the top nut.
A nice way of added colour and different grips to your darts, but I guess the idea never caught on really. Still something nice to have as it appeals to the curious side of me.