30 oz. Stainless Steel Polar Camel Tumblers feature double-wall insulation and a Slider lid. The mug has a narrower bottom to fit most standard cup holders. It is 2X heat & cold resistant compared to a normal tumbler. Polar Camels are made from 18/8 gauge stainless steel (18% chromium/8% nickel) - also known as Type 304 Food Grade.