19 CFR § 10.456 - Accessories, spare parts or tools.
§ 10.456 Accessories, spare parts or tools.
Accessories, spare parts or tools that form part of the good's standard accessories, spare parts or tools and are delivered with the good will be treated as a material used in the production of the good, if—
(a) The accessories, spare parts or tools are classified with and not invoiced separately from the good; and
(b) The quantities and value of the accessories, spare parts or tools are customary for the good.