Any tumbler that's coming along for the ride needs to be tough enough to keep up. YETI's fan-favorite Rambler 20 oz. Tumbler is made from kitchen-grade stainless steel with double-wall vacuum insulation to protect the temp of your beverage at all costs. Like the entire YETI Rambler Drinkware Family, the 20 oz Tumbler and MagSlider Lid are dishwasher-safe for easy cleaning. While the magnet on the included MagSlider Lid adds an additional barrier or protection for keeping drink contained and preventing heat or cold from escaping, this magnet slider is not leakproof and will not prevent spills. CAUTION: Not for use with carbonated beverages and should not be used as storage for food or perishables. Please see FAQ here for more details.