ULTRA CAPACITY BATTERY: Lithium battery with large capacity, screen turn off automatically. Don't need to worry about battery rechange issue daily. DURABLE KEEP HEAT COLD: The vacuum of cups and cups can block heat transfer. (After 24 hours at 100 C water, the temperature is maintained at about 40 C)WIDE APPLICATIONS: Whether you are traveling, at home, in the office or outdoor - the ideal companion. Simple and practical, it is the best Christmas gift for friends, family. SAFE & HEALTHY MATERIAL: The inner wall is made of 304 grade food grade stainless steel and the outer case is made of high quality 204 stainless steel. Of course, 100% does not contain BPA. WATERPROOF LED DISPLAY: Waterproof LED display that can be completely submerged in water. Just touch the LED screen and the temperature of the liquid will show on the LED screen. WATERPROOF LED DISPLAY: Waterproof LED display that can be completely submerged in water. Just touch the LED screen and the temperature of the liquid will show on the LED screen.