LANOVA HOME Vacuum-Insulated Unique Stainless Steel Travel Mug, 11-Ounce,Green Double Wall Vacuum Insulation Technology - The air between the two walls is sucked out, in order to prevent outside temperature to affect the liquid inside the mug. You can turn it upside down, shake it up, roll it, the liquid will not spill. Try it or get reimbursed! ?Keeps HOT liquid HOT and COLD liquid COLD for Hours. Cap is designed to be easy to clean and dishwasher safe Durable, impact-resistant construction and finger carry loop so it can go where you do