The day and night mug is a heat sensitive coffee mug that has a picture of the world on it. By default the mug shows nightime, darkness from space, only showing the lights that are visible from electricity, and when you pour hot liquid inside of it, it will change to daylight, making the mug much brighter as if looking at a globe. No longer will you have to wait to see if your coffee/urine is cold and undrinkable (no one likes cold urine), just look at your mug, and if the world is dark, your urine is cold, so dump it out and brew up a fresh batch. The day and night color changing coffee mug is made from ceramic, can hold up to 11oz of liquid, and is not dishwasher or microwave safe.