I have several such spools of DuPont nylon of different gauge widths that I have from a harpmaker now deceased. You could ask a very knowledgeable person in the trade, Betty Truitt , of Dragonwhispers Harps in California. It has been my understanding (please correct me if I am mistaken) that this bulk nylon string has not yet been drawn through a diamond die, to be perfectly cylindrical and therefore produce a tone pure enough for using on finely crafted harps . Fishing line, “weed-eaters” and other nylon string products would not need this refinement. As a stopgap emergency harp string on folk harps when you don’t have a music-quality string on hand, it is useful however until you can get a quality replacement.
You can contact Betty at (619) 473 9010, or by regular mail: Dragonwhispers Harps, 33920 Mount Laguna Drive, Mount Laguna, California, 91948.