Adjustable strap for shoulder or crossbody carry Packs into own pocket for easy storage & travel Stretch mesh pockets Take your Hydro Flask on a walk or hike, running errands, or to a festival. The Packable Bottle Sling keeps a low profile when not in use, but stays light when you need hands-free hydration. The small size fits all Hydro Flask standard mouth bottles and 16oz/18oz/20oz/24oz wide mouth bottles. The medium fits Hydro Flask 32oz/40oz wide mouth bottles.