Battery Color Changing Mug Category : For Home, For Men, For Women, Gamers, Kitchen, Under $20 Bathtub Caddy Tray Turtle Night Light Projector Bluetooth Beanie Headset Waterproof Bag This creative mug changes the color of the battery on it by heat sensitivity. That way you’ll know how much longer you have until you reach the cold sad end of the coffee. $8.22 Check it out