Most coffee drinkers would agree that a good cup of coffee can and should be had at any time, but they will likely also say that hot or cold coffee has a short perfect temperature life. Hot coffee must be hot, and ice coffee must be cold to give their dedicated coffee lovers a cup suited to their needs, we created the cadus coffee mug to best hold the coffee's ideal temperature. Following their cadus design, the coffee mug in this series has a double wall application to maintain your drink's hot temperature while protecting your hands from the heat. The set of two mugs are made of pristine hand-blown glass that can withstand a temperature of up to 350 degrees Fahrenheit; this heat can be from the microwave, the liquid itself, a dishwasher or even an oven! Similarly, cadus mugs are freezer safe, allowing hot coffee to be turned iced without having to change cups! By using only top-quality borosilicate-glass for mugs.