Our most popular running vest is now lighter and more comfortable! Updated for 2019, the Circuit™ Vest includes a 1.5-liter CRUX reservoir that delivers 20% more water per sip and is lighter weight for additional comfort. With a more streamlined dual sternum strap adjustment system, that also has integrated reflectivity, and a new 3D Micro Mesh, the Circuit is lighter, more comfortable and better ventilated. The secure zippered pocket fits most smartphones and the open front harness pockets are specifically designed for Quick Stow™ flasks should you need additional hydration. A one-size fits most design, means you can use it for a variety of activities and thanks to the side compression being highly adjustable it ensure a stable fit over any terrain.