Anyone know from this new product? Essentially it's a stability ball filled with some sand to add weight, or ballast, as the inventors call it. Here's a link to a video about it:

http://www.bosupro.com/scripts/cgiip.exe/WService=bosupro/itemdetl.html?item=18250-1a#VD

I know the promoters, having done various fitness workshops and trainings with them. I use stability balls and the BOSU balance trainer with my clients and I'm very pleased with those products. But I also use medicine balls, so I wonder if this new product is redundant.