I bought one after trying a run belt which wouldnt stay put on its tightest setting. I;m about 10st with a 28-29 inch waist. Decised to try the flashflo after all the good comments, only used it once & it did the job well, didnt bounce once I got the tightness correct, took a little while to get used to drinking from it as it took a little more effort.
On the whole highly recomended.