6402.91.40 - Having uppers of which over 90 percent of the external surface area (including any accessories or reinforcements such as those mentioned in note 4(a) to this chapter) is rubber or plastics except (1) footwear having a foxing or a foxing-like band applied or molded at the sole and overlapping the upper and (2) except footwear (other than footwear having uppers which from a point 3 cm above the top of the outer sole are entirely of non- molded construction formed by sewing the parts together and having exposed on the outer surface a substantial portion of functional stitching) designed to be worn over, or in lieu of, other footwear as a protection against water, oil, grease or chemicals or cold or inclement weather

This HTS classification covers footwear, specifically those with outer soles and uppers predominantly made of rubber or plastics, which extend to cover the ankle. The key defining feature of this category is that the uppers are composed of rubber or plastic for over 90% of their external surface area. This excludes footwear with specific construction elements like foxing or foxing-like bands, and also excludes certain protective footwear designed for harsh environmental conditions or as replacements for other footwear.

Within the broader category of "Other footwear, covering the ankle," this particular sub-classification distinguishes itself by its material composition and general design. It differs from sibling categories that might focus on specific protective functionalities, such as specialized active footwear with defined height limitations or insulation properties. This category encompasses a wider range of everyday footwear that meets the general criteria of rubber/plastic uppers covering the ankle.

The subcategories within 6402.91.40 provide further specificity based on intended wearers and statistical notes. The "For men" and "For women" subdivisions allow for gender-specific classification, while the "For infants" category, guided by statistical note 2, designates footwear for very young children. Finally, the "Other" subcategory serves as a residual, capturing any remaining footwear that fits the primary classification but does not fall under the more specific gender or infant designations.