This is a 8 inch (200 mm) protective ceramic tube for high temperature K-type thermocouples, for example for the model CR-02 . It will protect the thermocouple inside the oven, furnace or kiln from any contamination. This thermocouple protection tube is made from 95% alumina high temperature ceramic and can withstand temperatures over the full Type K range, up to 2500 degree Fahrenheit. This ceramic protection tube is now also available in 10 inch length, model CR-03-10