Lt's a work of art: Unique double walled glasses are designed to suspends drinks within an inner wall for an engaging optical effect. Double wall cups perfect for coffee with milk, lattes, cappuccinos, black coffee, tea and more, these glasses are a stylish and functional addition to any glassware collection. Insulated cup extremely lightweight, it is the perfect companion for your hot and cold beverages. Manufacturing process: Double wall glasses are mouth-blown by expert artisans using borosilicate glass. Borosilicate is stronger than traditional “soda-lime” glass and can be used for everything from drinkware to cookware. Due to the natural properties of the boron particles, the glass is held together tighter, resulting in a stronger, lighter glass. Borosilicate glass doesn’t need to be as thick as traditional glass to be just as strong due to the bonding capability boron oxide. Double glass design: Double wall glass allows your hot beverage to remain hot for a longer period of time while keeping the outer glass cool to the touch. Your cold beverages will remain cool inside while the outer wall remains free of condensation. Double wall glasses that breathe! A silicone vent at the base of each of Virgin forest Double Wall Glasses equalizes the air pressure between the two layers of glass when either hot or cold liquids are added. Permeable only to air, never water, the vent enhances durability and will never allow liquids to enter between the two layers. Light weight & high strength: While borosilicate glass is naturally lighter than traditional glass it is stronger and more resistant to temperature changes and scratching, rest assured that you are getting a scratch-resistant and break-resistant quality cup from normal everyday use.