A shoulder sling that carries the bottle so the backpack can stay at home. The sleeve is cut from 3.5 mm neoprene, thick enough to cushion an insulated bottle against a door frame, a park bench or a gravel path.
Two zipped pockets sit on the outside of the sleeve for a phone, cards and keys, which is usually the whole list for a walk or a class. The strap adjusts for length and can be carried on the shoulder or in the hand, and the sleeve itself takes bottles from 20 oz up to 40 oz, so it fits the tall insulated ones as well as a standard flask.
