Heatilator 10 lbs. Mortar (TRAD: 1 required, HERR: 2 required) (Birmingham). Refractory panels line the firebox, protect the metal surfaces and set the look of the fire. Panels are matched to a specific fireplace model and size, so confirm your model number and firebox width before ordering. Ships as a set sized for the firebox listed; replace cracked or spalled panels promptly to protect the firebox. Special order - contact us for a quote.