5509.99Subheading
Yarn; (not sewing thread), of synthetic staple fibres, mixed mainly or solely with fibres (other than wool, fine animal hair or cotton), n.e.c. in heading no. 5509, not put up for retail sale
Section XI — Textiles and textile articles
This is a 6-digit subheading — the most specific level of the international HS. Country tariff schedules extend it further; the US tariff lines (HTS) below refine it to 8–10 digits for duty purposes.
US tariff lines for this subheading are not in the bundled starter dataset yet — the full HTS schedule is coming soon. You can still search by code in the tariff simulator.