Piece Heat Insulated Borosilicate Glass CupThe product has double layer glass and thermisile properties. Heat resistant, Stylish, Elegant and Double-Walled Design. It is made of high quality borosilicate glass. Do not let your coffee get cold at home, at work, in the office. 300 mlBorosilicate Glass has a granite-like structure, It is very difficult to wear, does not scratch. As it provides resistance to high temperatures, it is also resistant to low temperatures. There is a round mark on the bottom of the glass due to the construction of the double-walled glass. It is not a defect. We recommend hand washing.