Threaded copper fasteners are most commonly specified in marine hardware (where saltwater corrosion resistance is essential), electrical grounding systems (where conductivity matters), and chemical or food-processing equipment where iron contamination must be avoided. Architectural and decorative applications also use copper fasteners for their appearance and patina characteristics.

When a fastener is made of mixed metals, classification generally follows the essential character of the article, which CBP typically determines by the predominant material by weight or value. A bolt with a copper body and minor steel components would likely remain in the copper fastener heading, but a mixed-material article should be reviewed carefully — and a binding ruling sought if the composition is ambiguous.