Double Wall: The double wall design keeps the cup safe to touch with hot drinks and free of condensation with cold ones. And also keeps your drinks hot or cold for longer than one layer glasses under the same conditions. Hand-blown: Thanks to the high-quality workmanship and experience of the glassblowers the glass is wonderfully light clear and smooth for easy and pleasant use. Borosilicate Glass: The use of high quality borosilicate glass the cup will not burst even at high temperatures. It is possible to pour hot water into the ice-cold mug. Freezer compartment is suitable and hand washing is recommended. All glassware is fragile so use and wash it carefully.