This Small Universal Rubber Stopper from Buon Vino is taller, made with a taper and of a different material than the rubber gum stopper so that it fits multiple sizes of carboys and does not pop out when wet. It also has a lip around the top so it won't push into the carboy either. - Small fits 3, 5, 6, and 6.5 Gallon Glass Carboys. For wine making or beer brewing.