The tapper of this flask, slightly more robust body, and locking cap make this a great flask for putting in my Salomon Pulse running belt or the pocket on the Century short. Of all the features, the HydraPak locking cap is the most important to me. The pictures online don't show how the locking cap works for those who aren't already familiar, but the lock is at the base of the cap and is super easy to use, just twist one way to open the valve and back the other way to close. There are marks on the cap that show you which side is open or closed. There are no leaks with this flask when I tuck it away horizontally, which happens every time with other non-locking flask caps. Additionally, carrying this flask as a pre-filled extra in the back of my running pack is great because I don't have to worry about leaks inside my pack either. Love this flask and the profile design of the flask body, very handy!