"The SkyFlask is my favorite and most used product for training or race days. In a 100 mile race I can use upwards of 20 flasks. This is what I use for my liquid calories and to carry water. The updated thumb hole makes it seem like you aren't holding a bottle in your hand. I also love the 150ml/250ml softflasks, they are the perfect size for maple syrup or homemade gels. I also use these for my liquid calories on shorter runs, or for my coke/energy drinks in races. These flasks are small but don't sleep on how much they can do for you! I don't like to carry too much gear when I'm on the run, and the filter cap means I'm able to filter water on the go! You simply scoop up the water in an empty flask, and the cap does the filtering while you're drinking. The cap works on any 42mm opening which makes it extremely versatile. I won't leave home without it in the summer months!”