Any tumbler that's coming along for the ride needs to be tough enough to keep up. YETI's fan-fovourite Rambler ® Tumbler is made from durable stainless steel with double-wall vacuum insulation to protect the temp of your beverage at all costs. Like the entire Rambler ® Drinkware Family, the Tumbler and MagSlider ™ Lid are dishwasher-safe for easy cleaning. 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 leakproof and will not prevent spills. Details 18/8 Stainless Steel: Made with kitchen-grade stainless steel, so they're puncture and rust-resistant. Double-wall Vacuum Insulation: Keeps cold drinks cold and hot drinks hot until the last sip. Dishwasher Safe: Because no one needs more work to do. Magnets: Makes for easy opening and closing.