K12 Hydro Flask 12 Ounce Cooler Cup Hydro Flask's new Cooler Cup is two great things in one: it's a can or bottle cooler, or with one quick switch, it's a 12 oz beverage cup. As a Cooler Cup, it's brilliantly versatile with a silicone sleeve that lets you slide in a narrow bottle or a can-all with the same snug fit. Pop off the sleeve and you have a 12 oz cup made to keep cold drinks cold and hot drinks hot. The ultimate win-win.