HTS code 9902.16.21 covers "Lithium thionyl chloride (LTC) batteries, annular in shape, measuring 30.48 mm or more but not over 152.4 mm in length, with an outer diameter of 10.16 cm or more but not over 127 mm and an inner diameter of 55.88 mm or more but not over 88.9 mm, certified by the importer as containing a lithium anode and a liquid cathode comprising a porous carbon current collector filled with thionyl chloride (SOCl2) (provided for in subheading 8507.60.00)" 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.