20 oz. Stainless Steel Polar Camel Mugs feature double-wall, vacuum insulation with a clear, slider lid. They are 2X heat and cold resistant compared to other tumblers. Polar Camels are made from 18/8 guage stainless steel (18% chromium/8% nickel) - also known as Type 304 Food Grade.  Not recommended for dishwashers, hand wash only.2