HTS code 9902.15.46 covers "Cast-iron cylinder heads suitable for use solely or principally with marine compression-ignition engines, such parts with cylinder bore over 125 mm and weighing over 32 kg each (provided for in subheading 8409.99.92)" 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.