Purchased this recently to use in a 1/2 Iron Man. The bottles hold a good amount of water and are easy to drink from while you're running. The bottles snap easily into place and stay in place pretty well. I had them fall out twice, the first time was my fault as I didn't check they were properly secured as I put on the belt and blasted out of transition. The second time it was after coming off a pretty decent hill. The bottles can be repositioned to where you need them so you can minimize bounce. Overall very happy.