High performance vacuum insulated double walled stainless steel construction. Keeps cold up to 24 hours (ice cubes recommended), keeps hot up to 12 hours. 18/8 food grade stainless steel, BPA free with no leeching effect, retains the taste of the beverages and does not impart any flavors; No toxic powder coating. Extremely durable, easy to carry, drink and clean, tight closure (even for carbonated drinks).