Oasis Value-Sets include genuine Oasis Bell-Bottle Water Bottles and Basic Hold-Guards paired for a perfect fit. Bell-Bottles feature rounded tops to discourage chewing and are color coordinated with the Hold-Guard. The Hold-Guard is sturdy metal with non-toxic powder coating. The guard hangs inside the pet's cage and protects water bottle and cap from chewing biting and gnawing damage. The easy to adjust hanger strap fits many sizes of aquarium-type pet environments (hangs over the upper edge) or wire cages (hanger straps slides through the wird side.) Suitable for fancy mice fancy rats gerbils hamsters sugar gliders and hedgehogs. 4 ounce Bell-Bottle with matching Hold-Guard.