SuperPet Critter Canteens www.ferret.com - $2.79 (16oz. size) Product Description: The Super Pet Critter Canteen is refreshingly easy to use just fill, cap and hang! Featuring a unique spring-loaded sipper tube to reduce leaks, the Critter Canteen includes a wire bottle hanger. Available in 16 oz. and 32 oz. capacities. RattyRat's Review: These water bottles function fine, but they are absolutely awful to use because you can't tell how much water is left in them. Why would a company make a fairly non-transparent blue water bottle!? It makes no sense to us.