Millstones and grindstones for milling, grinding, or pulping are classified under a dedicated heading based on their end-use application in food or fiber processing, while abrasive grinding wheels for metalworking or tool sharpening fall under separate headings. The distinction rests on the article's design, size, and the industry for which it is manufactured. A millstone's large diameter, flat working face, and grain-processing provenance typically make the classification straightforward, but composite or manufactured stones may require additional documentation of intended use.

Both natural stone millstones and those made from agglomerated abrasive materials fall within this heading when their primary purpose is milling, grinding, or pulping. However, the tariff subheading may differ based on whether the stone is of natural origin or manufactured, so importers should specify the material composition and production method on the commercial invoice to support accurate classification.