About this item IDEAL VOLUME: 15-Ounce; perfect for serving ice cream, coffee, whiskey, juice and others. ELABORATE DESIGN: durable double layer construction resists heat and prevents condensation. SAFE WASHING: safe for dishwasher and microwave use; not for use with metal utensils HIGH QUALITY: made of lead-free borosilicate glass for ultra clarity and brilliance. Absolutely no air bubble or water vapor in between the walls.(up to 520°F ) WARM REMINDED: There is a small hole in the bottom of the cup, which is the unique trace of the manual blowing process.Not a flaw!