I use this pack for runs that are less than around 15 miles because if I intend to go more than 15 miles, I need more than 1.5 L of fluid in the summer. I like it because it is lite weight and because it is nice and secure. No bouncing. The downside is that the bite valve leaks. What I have to do is to raise the bite valve high after each sip so that the fluid leaves the tube and returns to the pack.