9027.90.64.00 - Of instruments and apparatus of subheading 9027.20, 9027.30, 9027.50, 9027.81 or 9027.89

This HTS category, 9027.90.64.00, specifically covers parts and accessories for instruments and apparatus classified under subheadings 9027.20 (chromatography apparatus), 9027.30 (spectrometers, spectrophotometers, and colorimeters), 9027.50 (other measuring or checking electrical apparatus), 9027.81 (gas or dust analysis apparatus), or 9027.89 (other instruments and apparatus). These are typically components, assemblies, or ancillaries that are integral to the function of these advanced analytical or measuring devices. Examples include specialized optical lenses, detectors, flow cells, sample holders, or electronic modules designed for use with these specific types of analytical instrumentation.

This category is distinguished from its sibling, 9027.90.68.00 ("Other" parts and accessories), by its specific designation as parts and accessories *of optical instruments and apparatus* within the broader context of Chapter 90. While the sibling category would encompass parts for a wider range of analytical instruments not specifically covered by the optical subheading, this category is limited to those components that are either optical in nature or directly associated with the optical functions of the specified analytical equipment. The key differentiator is the direct link to the optical performance or components of the instruments detailed in the preceding subheadings.

As this is a leaf node within the HTS structure, there are no further subcategories to introduce. Therefore, classification within 9027.90.64.00 is definitive once it is determined that the part or accessory pertains to the enumerated analytical instruments and exhibits characteristics aligning with the general scope of parts and accessories for such equipment. The focus remains on the direct applicability to the optical aspects of the instruments covered by subheadings 9027.20, 9027.30, 9027.50, 9027.81, and 9027.89.