Alumina hollow ball castable is a new type of high temperature insulation material, it is made of industrial alumina in the melting furnace made of the crystal, a-Al2O3 microcrystalline crystal. To alumina hollow ball as the main body, can be made into a variety of shaped products, the maximum temperature of 1800 , high mechanical strength of products for the general light products several times, while the bulk density is only half of corundum products.