9109.90 - Other:

This HTS category, 9109.90, encompasses clock movements that are complete and assembled, excluding those that are electrically operated. These movements are the fundamental mechanisms that power timekeeping devices, comprising all the essential components such as gears, springs, and escapements, assembled into a functional unit. The scope of this heading is limited to the mechanical workings of clocks, not including the outer casings, dials, hands, or any electrical power sources or mechanisms.

Unlike its sibling category, 9109.10, which specifically covers electrically operated clock movements, this heading is reserved for movements powered by non-electric means, such as spring-driven mechanisms. This distinction is critical for accurate classification, as the power source and operational principle are key differentiators within the broader category of complete and assembled clock movements.

Within this classification, further distinctions are made based on physical dimensions. The subcategory 9109.90.20.00 specifically addresses movements that measure not over 50 millimeters in width or diameter. The subsequent "Other" subcategory is intended for all remaining non-electrically operated, complete, and assembled clock movements that do not meet the specific dimensional criteria of the preceding subdivision, providing a residual category for these mechanical timekeeping mechanisms.