The Wilderness Bottle Bag is an old favorite. The small size fits both 21 oz. and 28 oz. polyethylene Nalgene bottles (bottle not included). The bag attaches to your waist or pack belt with our signature wrap-around belt loop (shown at right with the large size Bottle Bag). It retains the bottle by both a top strap that wraps around the detent in the bottle body and secures with Velcro, and/or nylon cinch cords and a Delrin cord-lock.
While we love Camelbaks, we don't believe in putting all our eggs in one basket -- especially if it's a soft-sided bladder. Nalgene bottles have proven themselves safe and durable under the harshest conditions for many years.
The secondary images show a comparison between a 1-quart (32 oz.) WIlderness Bottle Bag (right) compared to 21-oz. Bottle Bag (center) and a Nalgene 28oz. bottle (left).