The Water Bottle Holder is the universal fit bottle bracket that attaches to any type of cage. Water Bottle Holder slides onto wire cages, hangs on any aquarium, or attaches to wooden walls with a screw. High grade steel with epoxy coating is sturdy and chew-proof. Perfect for holding 4 or 8 oz. Critter Canteens or other standard 4 and 8 ounce water bottles.