1 Piece of Thermal Insulated Borosilicate Glass Cup The product is double layer glass and thermosilver. Heat resistant - Stylish - Elegant and Double Walled Design. Made from high quality borosilicate glass. Don't let your coffee get cold at home, at work or in the office. 300 ml Borosilicate Glass It has a granite-like structure - It is very difficult to wear - It does not scratch - It is resistant to high temperatures and 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.