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. Borosilicate Glass, Mass Tinted, Chip Resistent. # Pieces In Set: 6 Included: 6 8.5 oz. Mug(s) Features: Chip Resistant, Microwave Safe, Stackable, Dishwasher Safe Capacity: 8.7 oz. Maximum Temp (f): 400 Degrees F Base Material: 100% Glass Care: Dishwasher Safe Material: Glass Country of Origin: Imported