STACKABLE AND INSULATED DOUBLE WALL DESIGN - This double-wall design allows for a pair of glass to be stackable for space saving. The 2-layer demitasse glass cups stay cool to the touch and keep drinks hotter or colder than normal glass or ceramics.LIGHTWEIGHT YET STRONG - Sweese espresso coffee mugs are made of mouth-blown borosilicate glass which is comfortable to hold and can be used for a long time.PERFECT FOR ESPRESSO MACHINE - Perfect for use with an espresso machine or small coffee maker, Sweese espresso coffee mugs hold 5 ounces to the rim. You can reheat in the microwave or freeze for cold beverages and it is also dishwasher safe, though hand-washing is recommended.AN IDEAL GIFT - Sweese espresso mugs make an ideal gift for family or friends on special occasions such as birthdays, housewarmings, weddings, parties, and Mother's Day. Wrapped in a gift box, they are sure to make a lasting impression.DESIGN - Featuring a small round hole design on the bottom, Sweese espresso coffee mugs are sealed to prevent water from entering and to allow the glass to breathe during use, ensuring they don't burst.