Any tumbler that's coming along for the ride needs to be tough enough to keep up and this tumbler is the perfect fireside companion or tailgate teammate. The Rambler® 20 oz. is made from durable stainless steel with double-wall vacuum insulation to protect your hot or cold beverage at all costs. While the magnet on the included MagSlider™ Lid adds an additional barrier of protection for keeping drinks contained and preventing heat or cold from escaping, please note - this magnet component is not leak-proof and will not prevent spills.