I made this piece on the pottery wheel using stoneware clay. It was fired in a natural gas kiln to 1800 degrees F, then dipped in a Copper Red glaze. Lastly, it was fired again to about 2300 degrees F. in a natural gas kiln. It is 100% functional, dishwasher safe and microwaveable. It measures about 4" tall by 5" wide. This mug is perfect for coffee, tea, hot coco and any other drink you can imagine.