HTS code 9902.14.69 covers "Polycrystalline fibers containing by weight over 70 percent of alumina and less than 30 percent of silica, the foregoing containing no alkaline oxides or boric oxide, presented in bulk (provided for in subheading 6806.10.00)" under the US Harmonized Tariff Schedule. This is the official duty rate charged by US Customs when this product is imported into the United States, sourced directly from the U.S. International Trade Commission and refreshed daily.