Vermiculite panels are commonly used as liners within wood burning appliances. They are in place to serve as a sacrificial layer to protect the steel firebox. They may have a little or a lot of thermal properties so OEM replacements are required based of your manufacture, model #, or serial #. Many companies indicate that replacement is necessary when cracks greater than the width of a coin are present or the material has thinned or can no longer support itself. We supply and install these components.