The boundary is the act of mounting. An insert that is loose, unattached, and presented separately — even if it is clearly destined for a specific tool holder — is classified under 8209 as an unmounted insert. Once the insert is brazed, clamped, or otherwise fixed into a tool body, the complete assembly is classified as an interchangeable tool under 8207, based on the tool's function (drilling, milling, turning, etc.).

Both headings cover cermet materials, but 8209 is the more specific provision for tool inserts in plate, stick, or tip form that are unmounted and intended for use as cutting elements. Heading 8113 covers cermet articles more broadly, including waste and scrap. Under GRI rules, the more specific heading prevails, so unmounted tool inserts of cermet are classified under 8209 rather than 8113.