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 5" tall by 5" wide. This mug is a must for coffee lovers who hate having to refill there mug every two sips.