Pyrometric cones are referred to devices that are used to measure heatwork during the firing of ceramic materials. These devices are ceramic clay wedges which are placed inside a kiln before firing. There are bar shaped devices also. The cone will bend at a certain temperature and it can be established by regular observation at what point particular temperatures are attained in the kiln. The E. Orton Jr. Ceramic Foundation directs to use a particular set of temperature equivalents for their cones, which melt at 34 different temperatures. These cones are each recognized with its own cone number: starting at 022 at the lowest temperature (1157 degrees F.), continuing to cone 01 and to the hottest at cone 12 (about 2420 degrees). Orton cones come in two normal sizes, temperatures varying between them a little. The Orton Cone Box Show, a ceramic art exhibition for small work conducted biennially takes the Orton Cone company's pyrometric cone box as the size limitation for submissions.