Tempilstik, over 80 years of accuracy, confidence, and compliance, is the original temperature indicating crayon with the best combination of precision and convenience for surface temperature measurement. Specifically designed for accurate temperature indication in pre-heating, interpass, and post-weld heat treating applications, Tempilstik is the industry's leading choice for use in the most critical jobs. Please note that the color of Tempilstiks is not part of their function, as the temperature signal is achieved by melting. The indicating color is subject to change without notice.