This Coffee Tumbler Mug is with Double-Walled vacuum technology which can keep coffee warm for 6+ hours, beverages cold for 12+ hours.Tumbler Cups inner are made of Food-Grade 304 stainless steel which is non-toxic and healthy. The interior is electropolished. The outer layer is coated with anti-sweat powder to keep your tumbler dry and clean. The coffee mug are easy to hand wash or wash great in the dishwasher. So convenient, no need to worry about cleaning the best partner for your journey.