The wall glass cups are designed to keep your hands cool with hot drinks and free of condensation with chilled glassware beverages. Insulated design for perfect drinking temperature- keep your drink hot or cold for longer. There is a BUBBLE AT THE BOTTOM of each glass-to maintain the air space between the layers and prevent cracking. These Heart Shape light weight double wall, insulated Tea and Coffee cups are perfect for cappuccino, latte, espresso, tea, juice, iced beverages, or smoothies.Coffee is one of those things you just can t afford to mess up. You need its magic, you need its power, you need the right glass for it. This coffee mug is crafted of fine Spanish tempered glass. It is thermal shock resistant, making it safe for the microwave and less prone to shattering. A convenient handle allows you to hold it without burning your hands, and when you re done using it simply deposit in the dishwasher to get it sparkling clean for next time.