Smart Flask uses a double wall, vacuum-insulated design to keep your favorite beverages cold for 24 hours or hot for 6 hours. No more warm water or cold coffee. Vacuum insulation means you never need to worry about sweating in your gym bag, backpack or on your desk. We incorporate a wide mouth opening so your Smart Flask will accommodate ice cubes or even fruit for a refreshing drink and it makes cleaning easier. Your Smart Flask is made of food grade 18/8 Stainless Steel which is BPA and phthalate free. The stainless steel will not have unwanted odors or lingering flavors.