Any tumbler we bring on the road needs to be durable enough to keep up. Our 20oz Rambler® tumbler is made from stainless steel with double-wall vacuum insulation to protect your drink’s temperature at all costs. Like the entire Rambler® family, the 20oz tumbler and MagSlider™ lid are dishwasher safe. The included MagSlider™ lid magnet adds an extra barrier of protection for your drink and prevents heat or cold from escaping. This sliding magnet is not airtight and will not prevent spills.