Screws are threaded fasteners that advance by rotation, while nails are driven by impact and have no thread. Self-tapping screws (731814) are classified here even though they create their own thread, because they still advance by rotation. An article that is driven rather than turned belongs in heading 7317.

Mixed fastener kits are generally classified under the General Rules of Interpretation, often as the component that gives the set its essential character or, if that cannot be determined, under the heading that occurs last in numerical order among those applicable. A binding ruling from CBP is advisable for recurring kit configurations to ensure consistent treatment.