8404.10Subheading
Boilers; auxiliary plant, for use with boilers of heading no. 8402 or 8403 (e.g. economisers, super-heaters, soot removers, gas recoverers)
Section XVI — Machinery and mechanical appliances; electrical equipment; parts thereof; sound recorders and reproducers, television image and sound recorders and reproducers, and parts and accessories of such 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.