Shaken or stirred, the Glass Martini FREEZE™ Cooling Cup keeps your drink at the optimal temperature. Our cooling gel freezes solid inside the double-walled chamber, providing insulation that keeps your drink cold for longer. Freeze the cups upside down for at least two hours to keep your drink between forty-three and fifty-three degrees Fahrenheit. Each cup is constructed with an insulated silicone band for comfortable handling. The set includes two 9 oz cups. Hand wash only.