This Bottle Sling is the simple solution to transporting your H20 hands-free. That way you can eat snacks, skip rocks, or indulge your dog in a riveting round of fetch. Mount it to the HitchPoint Grid on any Hopper Soft Cooler (or the Camino Carryall Bag). But if you're lookin' to hike light, clip on the removable carrying strap, sling it over your shoulder, and enjoy the journey up to that gotta-see-it viewpoint. The small is sized to fit the 18 oz Rambler Bottle. Rambler Bottle sold separately.