7304.39.00.20 - Having an outside diameter less than 38.1 mm

This HTS category, 7304.39.00.20, specifically classifies seamless tubes, pipes, and hollow profiles made of iron or nonalloy steel with a circular cross-section. The defining characteristic of items falling under this subcategory is their outside diameter, which must be strictly less than 38.1 mm. These are typically used in applications requiring smaller diameter tubing, such as instrumentation, small bore fluid conveyance, or structural components where minimal dimensions are critical.

The primary differentiator for this category lies in its narrow outside diameter specification. It is distinct from its sibling categories which cover larger diameter tubes. For instance, a tube with an outside diameter of 40 mm would fall into a different sibling category, as would one with an outside diameter of 10 mm. This precise measurement is the key criterion for distinguishing between these closely related classifications, ensuring accurate tariff application based on physical dimensions.

As this is a leaf node within the HTS structure, there are no further subdivisions. Therefore, classification within this category is solely determined by the material (iron or nonalloy steel), construction (seamless), cross-section (circular), and the specific outside diameter being less than 38.1 mm. Importers and exporters must verify these attributes to ensure correct entry.