5402.51Subheading
Yarn, synthetic; filament, monofilament (less than 67 decitex), of nylon or other polymides (not high tenacity or textured), single, twisted more than 50 turns per metre, not for retail sale, not sewing thread
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.