Orton Pyrometric Cones (Self Supporting)Self Supporting, Box of 25 Pyrometric cones are used worldwide to monitor ceramic firings in industrial kilns, pottery kilns, and small hobby kilns where the consistent temperature is important to the quality of the final product being fired. Pyrometric cones measure heat work, the effect of time, and temperature. Over time, kilns sometimes drift from their setpoint even though "Nothing has changed". Pyrometric cones will be the first to let you know