Over the past ten years, the collection has earned 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. The Bistro Double Wall Glasses keep hot drinks hot and cold drinks cold. It is a perfect glass line for people enjoying a whole range of beverages, from ice cold drinks to espresso or cafe latte. Create a truly gourmet dining experience with Bodum's Bistro double wall mugs. The collection's unique structure makes for a beautiful presentation of single-serve soups and desserts. Perfect for entertaining small groups and large parties. A silicone vent at the base of each of Bodum's Double Wall Glasses equalizes the air.