Thats the first I've seen of them. They look like the old hollow base bullets that the base expands up to bore diameter on firing. I've used the sabots since the early 90's and have been pleased with them. The plastic fouling is alot easier to get out than lead or copper that can be left in the bore. You would think that if you didn't get the copper fouling out perhaps it would trap the corossive black powder underneath and possibly pit the barrel? Let us know what you think about them, they look interesting.