Our Rambler 20 oz. is made from durable stainless steel with double-wall vacuum insulation to protect your hot or cold beverage at all costs. Like the entire Rambler Family, the 20 oz. Tumbler and its 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