6207.99 - Of other textile materials:

This HTS category, 6207.99, encompasses men's or boys' singlets, undershirts, underpants, briefs, nightshirts, pajamas, bathrobes, dressing gowns, and similar articles that are not knitted or crocheted and are made of textile materials other than cotton or wool/fine animal hair. The key differentiator for this heading is the textile composition.

While the broader Chapter 62 and heading 6207 cover a range of men's and boys' undergarments and sleepwear, the distinction at the 6207.9x level lies in the primary material. Category 6207.91 specifically addresses articles of cotton. Therefore, 6207.99 is reserved for items constructed from a variety of other textile materials, excluding those primarily made of cotton, wool, or fine animal hair.

To further refine classification within 6207.99, subcategories exist to address specific material compositions. These include provisions for articles containing a significant proportion of silk (70% or more by weight), as well as a general category for items made of man-made fibers, and an "other" category for residual textile materials not otherwise specified. This hierarchical structure ensures precise classification based on the dominant fiber content.