Retail sets put up for sale together are classified under GRI 3(b) by the component that gives the set its essential character, or if no single component dominates, by the heading that appears last in numerical order (GRI 3(c)). Importers should document the composition and relative value of each component and consider requesting a CBP binding ruling for high-volume combination sets.

Ballpoint pens use oil-based ink and are classified under a specific HTS heading for ballpoints, while rollerball pens use water-based or gel ink and fall under a separate heading for other pens. The distinction is meaningful because the two headings can carry different duty rates and different Section 301 exposure depending on origin, so ink type should be clearly stated on the commercial invoice.