Other Springs of Iron or Steel (Not Leaf or Helical)

Hairsprings are extremely fine, flat-spiral or coiled springs used in precision instruments such as clocks, watches, and measuring devices. They are specifically enumerated at 7320901000 and are distinct from the wire-form and other general-purpose springs in the remaining lines of this heading. Importers of precision instrument components should confirm whether the article meets the hairspring definition or whether it falls under a more specific instrument-parts heading.

The key question is whether the spring is wound in a true helical coil — a continuous spiral of uniform pitch around a central axis. If the geometry is helical, heading 732020 applies; irregular coils, flat spirals, volute forms, or other non-helical configurations fall to 732090. When the geometry is ambiguous, a binding ruling request to CBP provides the most defensible classification position.