The YETI Rambler Vacuum Insulated Tumbler is made from durable stainless steel with double-wall vacuum insulation to protect your hot or cold beverage at all costs. The Rambler is 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, it is not leak proof. Features18/8 Stainless Steel Double-wall Vacuum Insulation Dishwasher Safe