BODUM premiered its line of double wall glasses in 2002. The inventive design coupled with timeliness style made these glasses an instant classic. Over the past ten years, the collection has earned numerous awards and expanded to include a variety of styles and sizes. Made of heat-resistant borosilicate glass,and individually mouth-blown by expert artisans, the double wall construction creates a highly effective layer of insulation. Hot drinks stay hot longer, while the glass remains cool to the touch, and cold drinks stay cold without producing messy condensation. The result is endless serving possibilities. The patent pending ydrophobic silicone vent at the bottom of each glass equalizes pressure within the walls of the glass with the outside air pressure. The glass will self-adjust to any temperature liquid, and the vent is only permeable to ir, not water, so whether your beverage is hot or cold it will never allow fluids into the interior of the glass layers.