Get in and out of aid stations without delay using the On Soft Flask 500ml. The Soft Flask uses safe and reliable BPA-free materials in a small, collapsible design that shrinks as you go to eliminate any water sloshing and keep you focused on the run ahead. With its wide opening, you can quickly and easily fill the Soft Flask, while a high-flow valve releases fluid faster to keep you hydrated without any fuss. for storage, the bottle easily collapses to fit in any vest pocket or belt.