Double-walled glasses mean no more burned fingers or messy “sweat” rings. A layer of air within these double-walled glasses insulates drinks to keep them hot or cold, so they won’t “sweat” like regular glasses. Heat-resistant, extra-tough borosilicate glass is microwave and dishwasher safe. Glasses are available in 2 sizes-Tumbler and Coffee Mug; the Beverage Glass is no longer available. Sets of 4.