The Favourite Yeti Rambler® 591ml Tumbler is made from durable stainless steel with double-wall vacuum insulation to protect the temp of your beverage. The tumbler and MagSlider™ lid are dishwasher-safe for easy cleaning. The magnet on the 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 leakproof and will not prevent spills.