4107.91 - Full grains, unsplit:

This HTS category, 4107.91, encompasses full-grain leather derived from bovine (including buffalo) or equine animals. A crucial characteristic is that these hides are unsplit, meaning the full thickness of the hide remains intact. This leather has undergone further preparation beyond basic tanning or crusting, and it is free from hair. This category specifically excludes leather classified under heading 4114.

The distinction between 4107.91 and its siblings lies in the splitting of the hide. While 4107.91 covers *full grains, unsplit*, the sibling category 4107.92 pertains to *grain splits*, indicating that the hide has been divided into layers. The category 4107.99 covers *other* full grains, unsplit, which would typically include those not specifically enumerated elsewhere within this grouping and that don't fit the definitions of the other subcategories.

Within 4107.91, further subdivisions exist to specify the animal origin of the leather. The primary subcategory, 4107.91.40.00, specifically identifies buffalo leather. Additional subcategories, not explicitly detailed here, would exist to classify other types of bovine or equine leather that fall under this "full grains, unsplit" designation, allowing for more precise import/export declarations.