Living World water bottles are made with durable plastic and have leak-proof spouts. They attach easily to the outside of the cage with a wire holder. The closed system helps to keep contaminants out and is easy to clean. Water bottles should be re-filled daily with fresh water. Periodic cleaning with tepid, soapy water is recommended, just rinse thoroughly before re-filling with fresh water. Available in 5 sizes: Extra Small (2 oz.) Small (4 oz.) Medium (8 oz) Large (16 oz.) Extra Large (32 oz.)