* Set of 4 handmade, double-wall thermo mugs, each mug boasting a unique curvature that holds 5.4 ounces. These unique double walled glasses are designed to suspends drinks within an inner wall for an engaging optical effect * Made of heat and condensation-resistant borosilicate glass, which is stronger and more durable than common glass that gives a smooth finish and a crystal clear look. Keeps your liquid hot while keeping your hands cool. * Our espresso mug is made of high quality borosilicate-glass, Safe for dishwasher and microwave use 3.7"W x 3.58"H 5.4 Ounces