These Self Supporting Orton Pyrometric Cones are used on a shelf inside a kiln to determine when a firing is complete, if the kiln provided enough heat or if there was a problem during the firing. This style of cone does not require a cone holder. These Orton cones are made from carefully controlled compositions so that they bend in a repeatable manner over a very small temperature range. When the cone tip reaches a point level with the base it indicates it is properly fired. Cones have been used in ceramic firings for more than 100 years and Orton has the history and experience to provide the very best product.