HTS code 9902.13.09 covers "Modacrylic staple fibers containing 35 percent or more but not over 85 percent by weight of acrylonitrile units and 2 percent or more but not over 3 percent of water, not pigmented (ecru), crimped, with an average decitex of 1.7 (plus or minus 10 percent) and fiber length of 51 mm (plus or minus 10 percent) (provided for in subheading 5503.30.00)" 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.