At a glance, this mug might look like your everyday drinking vessel, but look again. It's loaded with top-to-bottom insulation to keep your coffee hot from the first pour to the last sip. And it's a space saver. When the lid is removed, the built-in grooves on the bottom help it stack perfectly on top of another one just like it. So whether you're storing it in the cabinets or packing it up for an adventure , it one-ups the average mug. Like the entire Rambler Family, this stackable mug and included MagSlider Lid are dishwasher safe making them easy to clean, but please note , the smooth-sliding magnet component is not leakproof and will not prevent spills. Important: Do not place mug over external heat source or open flame. Vacuum seal or other damage may occur.