The stainless steel mugs are double-walled, vacuum insulated to thermally regulate your drinks so you can enjoy them to the last refreshing drop. Warm drinks stay warm for more than 6 hours, and cold drinks stay cold for up to 24 hours. Ideal for juices, coffee, smoothies, cocktails, iced tea and water. Prevents the transfer of cold or heat to the outside of the cup with a straw for easy drinking.