9002.90.40.00 - Mirrors

This HTS subcategory, 9002.90.40.00, specifically covers mirrors that are designed to be integral parts of or fittings for optical, photographic, cinematographic, measuring, checking, precision, medical, or surgical instruments and apparatus. These are not general-purpose mirrors, but rather those engineered with specific optical properties or mounting mechanisms to fulfill a precise function within a larger instrument. Examples include mirrors used in telescopes, microscopes, surveying equipment, medical diagnostic devices, and camera systems, where precise reflection and image manipulation are critical.

This classification is distinct from its sibling category, 9002.90.20.00, which pertains to prisms. While both prisms and mirrors are optical elements, prisms are characterized by their ability to refract or disperse light through their angled surfaces, whereas mirrors are designed to reflect incident light. The essential difference lies in the primary optical phenomenon they exploit: refraction for prisms and reflection for mirrors.

As this is a leaf node, there are no further subdivisions. Classification within this subcategory relies on the determination that the item is indeed a mirror and that its intended use is as a component or accessory for one of the specified types of instruments or apparatus. The material of the mirror is generally secondary to its function and mounting as part of a specialized instrument, although the base material of the optical element itself falls under the broader scope of Chapter 90.