A good-quality lightweight ceramic block for soldering and kiln firing. The small holes in this ceramic block help to dissipate heat from the workpieces. Max temperature is 2000 degrees F. New size 5 1/2" x 7 13/16" x 1/2". Works great as a kiln shelf for firing glazes. Kiln door can be opened during firing, without risking thermal shocking shelf. When using for soldering or torch firing, it is recommended to place on solderite board, kiln shelf, fiber blanket, or tripod to keep heat from getting table too hot. The heat is not reflected like the solderite board, but is absorbed and some is passed through onto the surface below.