High strength polycrystalline alumina fiber bulk is manufactured by the globally advanced "sol-gel" process, has excellent fire resistance and heat resistance. In addition, it also has high tensile strength and chemical corrosion resistance. Widely used in fields such as power, aerospace, metallurgy, and chemical engineering. For example, used for insulation protection of high-temperature equipment such as heat treatment furnaces, high-temperature kilns, and gas turbines. It can also be used in areas such as firewalls, fire doors, floor sound insulation, and insulation.