Parts and accessories that are identifiable as suitable for use solely or principally with a machine tool of headings 8456–8465 are classified here under 8466, not with the machine itself. If a component is imported separately and meets that specificity test, it falls under the appropriate 8466 subheading. Components imported together as part of a complete machine are generally classified with the machine.

Chucks and collets that function as work holders classify under 846620 (work holders for machine tools), while tool holders and self-opening dieheads classify under 846610. Both subheadings cover accessories for the full range of machine tools in headings 8456–8465, so the distinction is functional—whether the device holds the workpiece or the cutting tool—rather than by parent machine type.