2-spout carboy cap for 3, 5, 6, and 6.5 gallon glass carboys. The two different size spouts allow you to connect a variety of fittings and use it in multiple ways. Insert a standard aitlock in the larger center opening. For an easy way to transfer liquids, insert a racking cane down the center tube, and blow or pump co2 into the smaller opening to start a siphon.