Corkcicle products use a first-of-its-kind, proprietary layer of insulation. In between the two walls of vacuum sealed 18/8 food-grade stainless steel, there’s a third layer that keeps drinks cold for up to 20 percent longer than other insulated bottles and cups. All components of their drinkware are BPA free. Keeps your favorite drinks cold for 9+ hours or hot for up to 3.