Ceramic Fiber Board Insulation (HD, 2300F)(1/2"x24"x24") 4 Square Feet (SF) Single Board Pack for Wood Stoves, Ovens, Forges, Kilns, Furnaces, Smokers 2300F (1260C) peak and 2100F (1149C) continuous use with a melting point of 3200F (1760C) MADE IN THE USA. Denisty is 23-28 lb/ft3, MOR 200 PSI (Green), 65 after firing. 47-52% Al2O3, 48-53% SiO2, 5-8% Loss on ignition (LOI) . Typical Shrinkage at 24 hours @ 2000F is &lt;5%.