With an insulated double wall, Bodum's Bistro mug stays cool to touch when serving hot beverages and prevents messy condensation with cold refreshments. Perfectly streamlined without many edges and corners, Bodum's Bistro thermal double wall mug is great for everyday use, superb for everything from hot drinks to cold brews. Made of heat-resistant borosilicate glass, and individually mouth-blown by expert artisans, this double wall mug features excellent insulation properties. Hot drinks stay warm longer, while the mug remains cool to touch and cold drinks stay cool without any messy condensation. Microwave and oven safe up to 180°C, Bistro is also dishwasher safe., , How the Insulation Works:, A silicone vent at the bottom of each mug equalizes pressure within the walls of the mug with the outside air pressure. As a result, the mug self-adjusts to the temperature of the liquid. Only permeable to air, not liquids, whether your beverage is hot or cold, the vent never allows fluids into the interior of the glass layers.