STACKABLE AND INSULATED DOUBLE WALL DESIGN - Pair of glass can be stackable to save space. 2-layer demitasse glass cups stay cool to touch, without burning hands, it keeps hotter and colder than normal glass and ceramics.LIGHTWEIGHT BUT NOT FLIMSY - Espresso coffee mugs feel lightweight, but they are true glass since Sweese glass is made of mouth-blown borosilicate glass which is lighter and durable than normal glass, feeling comfortable in hands. Can be used for a long time.PERFECT FOR ESPRESSO MACHINE - Each of the coffee mugs set holds 5 ounces to the rim, which is enough to go with an espresso machine as well as a small coffee maker, perfect for cappuccino, shot espresso. What’s more, you can reheat in the microwave or you want to drink a cold beverage, safe in the freezer. It is also dishwasher safe, but recommend washing by hand.AN IDEAL GIFT - Beautifully shaped and well wrapped in a gift box, these espresso mugs could be the ideal gift for your family or friends especially on special occasions such as birthday, housewarming, wedding, parties, Mother’s Day, etc.DESIGN--There is a small round hole design on the bottom of the glass coffee cup, in order to prevent glass mugs burst when using, allows the glass to breathe in the process. It is sealed, the water would not go in.