Hi Eric,

What does this SI stand for?? Plus, if I'm doing my conversion factor correctly- 8 to 10kg's equals to about 16 to 20 pounds.- that's alot of water. I personnally have a camelbak- The one a have holds 70 oz's. (adding probably 2 pounds to my person.) I have to also say -THEY ARE GREAT!- I would hope that people used them only for drinking (water....) purposes and not abused for adding weight to their person. Thus, there might be a possibility to allow them for racing.