INSULATED GLASSES: the double-walled coffee glass is designed to keep your drinks hotter for a longer period of time, all while ensuring that your hands remain cool and comfortable. STACKABLE DESIGN: these stacking coffee cups are designed for easy storage, so theyll take up less space in the cupboard.. LIGHTWEIGHT GLASSES: made of high-quality borosilicate glass, those coffee cups are perfect for everyday use. DISHWASHER-SAFE: its easy to keep these cortado glasses clean, as they can be popped into the dishwasher.