HTS heading 4107

Leather further prepared after tanning or crusting, including parchment-dressed leather, of bovine (including buffalo) or equine animals, without hair on, whether or not split, other than leather of heading 4114 — 88 codes under this heading, with the duty on each.

42 of these lines state no rate of their own and inherit one from the line above, which is how the schedule is read. Each says which line it came from.

Source: Harmonized Tariff Schedule of the United States, U.S. International Trade Commission (public domain). Classification and the duties that finally apply to a shipment are a licensed customs broker's call.