The Lixit Bird Waterer allows you to give your birds clean healthy water all the time. The self-contained glass bottle keeps water clean and the unique design prevents water from getting all over the cage. To access their water, birds simply manipulate the stainless steel ball at the end of the tube. If the bird isn't touching the stainless steel ball, no water is released or drips out. Easy to install and fits most cages. The rubber stopper is non-toxic and USDA approved. All components can be sterilized. Includes mounting hardware. Small is ideal for Canaries, Cockatiels and Finches. Medium is designed for birds such as Conures, Quakers and Senegals. Large is made for African Greys, Cockatoos, Macaws and other large birds.