9005.90 - Parts and accessories (including mountings):

This HTS category, 9005.90, encompasses parts and accessories for optical instruments classified under heading 9005, specifically those relating to binoculars, monoculars, and other optical telescopes, as well as astronomical instruments. This broad classification includes components such as lenses, prisms, focusing mechanisms, eyepiece assemblies, mounting hardware, and protective covers, provided they are designed for use with instruments of heading 9005.

Distinguishing this category from its siblings, 9005.10 (Binoculars) and 9005.80 (Other instruments), is crucial. While those headings cover the complete assembled instruments themselves, 9005.90 is exclusively for the constituent parts and accessories. Therefore, if an item is a functional component or an ancillary item that contributes to the operation or usability of a telescope or similar optical instrument from heading 9005, but is not the complete instrument, it will fall under 9005.90.

The subcategories within 9005.90 provide further specificity based on the materials or complexity of the parts. 9005.90.40.00 specifically covers parts and accessories that incorporate goods classified under headings 9001 or 9002, which typically refer to optical elements like lenses and prisms themselves. The remaining parts and accessories, which do not specifically incorporate such goods or have other defining characteristics, are classified under 9005.90.80.01. This distinction allows for more precise tariff application based on the nature of the component.