Our line of Mullite Protection Tubes include a wide range of diameters, lengths, and mounting fittings to meet most needs. These protection tubes are available with a plain open end, ceramic collar or a choice of several metal fittings with various thread sizes. The composition of mullite consists mainly of 70% Al203 and 28% SiO2. These tubes are cast with one end closed and they are gas tight. The maximum service temperature is 2,700 degrees Fahrenheit.