There are cases where you may need a large drinker for a cage. Cases where you have to be away for a few days or more, your cage is large and has multiple birds and you need to offer a larger drinker, etc. The unique design of the Spanish large Cage Drinker allows you to slip the base through the wires and lock it in place. The bottle also slips off the base for easy filling as well as being opaque which allows you to see the level of water. The base that holds the water is a corrosive resistant aluminum. Holds a bit over two quarts. Great for pigeons, poultry and cage birds. Comes with wire bracket to hold bottle to cage. 33 oz.