The Magisso Cooling Ceramic Glasses allows you to keep water, wine or your favorite drinks colder longer even in the hottest weather without any ice cubes. Just soak the glass for a minute under water or a running tap for the cooling effect to start. The Magisso Cooling Ceramic Glasses will be approximately 40% cooler than the ambient temperature. For special occasions you can also write on the non-slip surface with normal chalk- Don't lose your Glass. Not only does it keep the cold content cold, it also keeps the hot drinks warmer for longer. Enjoy!