HTS code 9902.13.37 covers "Acrylic staple fibers, carded, combed or otherwise processed for spinning, containing by weight 92 percent or more of polyacrylonitrile, not more than 0.01 percent of zinc and 2 percent or more but not over 8 percent of water, such fibers dyed or raw white (undyed), such fibers with an average decitex of 11.0 (plus or minus 10 percent) (provided for in subheading 5506.30.00)" 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.