- The thermos mug is made of "food-grade" stainless steel with an automatic locking function. To take a sip, press and hold the button. If you release the button, the drinking hole will automatically close. Thanks to the well-thought-out design, the lid is airtight, but at the same time it can be quickly and easily disassembled. The thermos mug is convenient to use with one hand. Suitable for hot and cold drinks. Capacity: 300ml. When using with hot drinks, steam may accumulate under the lid under pressure. When you press the button for the first time to release the steam, hold the thermos mug vertically and at a safe distance from your face. - Hold the button to take a sip. Release it to automatically lock the lid. - Airtight lid. - Food-grade durable 304 stainless steel. - Double-walled with vacuum insulation. - Keeps drinks hot for up to 7 hours.