"Great Idea... Almost there. Needs some work."
I have used mine dozens of times. They are great when you are the type of runner that doesn't like to hold things in your hands, but you armed going for long enough to merit a pack on your back. So, in come these bad boys. They are great while they are full. But, where they fall short is when you start drinking the water. When you get below half of the fluid the bottom of the flask would not stop bouncing around! It drove me nuts. Enough to take them off and just hold the flask on my hand (and I hate having things in my hands). If you are a crazy like me then I would not recommend these. If you are a bit more stable and easy going, these will rock your world. Quality is awesome as usual. Innovation is so close. Just need a could tweaks on how to secure the empty flask then I am good!