8531.90 - Parts:

This HTS category, 8531.90, specifically addresses "Parts" of electric sound or visual signaling apparatus. It encompasses components, subassemblies, and individual pieces that are designed to be incorporated into or used in conjunction with the signaling apparatus described under heading 8531. This includes, but is not limited to, circuit boards, housings, connectors, and internal mechanisms, provided they are primarily intended for the signaling devices classified in this heading and not independently functional or classifiable elsewhere.

Unlike its sibling categories, which classify complete signaling apparatus such as burglar or fire alarms (8531.10), indicator panels (8531.20), or other finished signaling devices (8531.80), this 8531.90 category is exclusively for the constituent parts. For instance, a complete burglar alarm system would fall under 8531.10, while a replacement circuit board specifically manufactured for that alarm system would be classified here under 8531.90. The key distinction lies in the article's completeness and primary function: finished apparatus versus components.

The subcategories under 8531.90 further refine the classification of these parts. "Printed circuit assemblies" specifically denote populated circuit boards that form an integral part of the signaling apparatus, containing electronic components and performing specific functions. The "Other" subcategory captures all other parts not specifically classified as printed circuit assemblies, encompassing a broader range of mechanical and electrical components that are essential for the operation of the signaling devices. This hierarchical structure allows for precise identification and duty assessment based on the nature of the part.