I've seen them, but not used them, can't see any advantage of using them over an olivette. Another thing I have doubts about when buying unusual weights is what they are made of, some countries still use lead in sizes up to 1oz.
Non lead for sure TrickyD. Unlike and olivette they still have a split you can use. So you can use them as shot. The advantage I see is when float fishing the wagger as the main weight beside the float. Can move on the line under a small piece of silicone without any line damage. A small number 8 or float stops either side for easy movement. I like to try new ideas that might make like a bit easier.
Ah, right, so they can be taken on and off similar to the quick change feeders. Still think a good quality shot is as good, but as you say, you won't know how good or bad things are until you try them.