The insulating quality of the double wall glasses keeps hot drinks hot for a longer period of time, and keeps cold drinks cold longer. And, they look darn cool, with your beverage seeming to float inside the glass walls. Another nice thing about them is that there is no condensation on the outside when you serve cold drinks, therefore no messy rings on your table. And by the way, they're great for ice cream as well. Pilatus glasses are made from borosilicate glass and are dishwasher safe.