Since 1945, when Duralex invented the glass tempering process, the name Duralex has been associated with toughened glassware, utilizing their proprietary process. Dishwasher, microwave and freezer safe. Mass tinted, chip resistant  # Pieces In Set: 6 Included: 6 Mug(s) Features: Dishwasher Safe, Microwave Safe, Stackable, Chip Resistant Capacity: 8.7 oz. Maximum Temp (f): 400 Degrees F Base Material: 100% Glass Care: Dishwasher Safe Material: Glass Country of Origin: Imported