Happy Sales Set of 6 Heat Resistant Double Wall Glass Teacup Sake Cups, Clear Happy Sales 2 oz. Heat Resistant Double Wall Glass Teacups or Sake cups. Material: Heat-resistant Borosilicate glass (-20 DegreeC -- 150 DegreeC) Double wall keeps drinks hot or cold. Size: 2.5"D x1.5"H Dishwasher safe but Hand wash recommended.