Tariff classification of agglomerator filter elements turns on specific coverage as oil filters, not the residuary heading.

Filter elements used in agglomerators were held classifiable under tariff heading 8421.23 as oil filters for internal combustion engines because the element's essential function was filtration, with water separation occurring through that process. The fact that the filter was installed away from the engine did not exclude it from the specific entry, as the heading did not require physical placement inside the engine. The residuary heading 8421.29 could not apply where the goods were specifically covered by the more specific tariff provision.

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Issues: Whether filter elements used in agglomerators are classifiable under tariff heading 8421.23 as oil filters for internal combustion engines, or under tariff heading 8421.29 as other goods.

Analysis: The literature describing the product showed that an agglomerator combines fuel filtration with water separation, but the element itself performs the essential function of filtration. Water separation occurred through the filtering process, and the device remained a filter element rather than a distinct article falling outside the specific entry. The fact that the filter was installed away from the engine did not take it out of the scope of oil filters for internal combustion engines, because the heading did not require the filter to be physically inside the engine. A residuary heading could not be applied when the goods were specifically covered by the more specific tariff entry.

Conclusion: The filter elements were correctly classifiable under tariff heading 8421.23 and not under tariff heading 8421.29.

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