Hatch Premium Braided Fly Line Backing - 100, 150, 200, 250, 300, 350, 400, 600 up to 3000 Meters Hatch's Premium Braided Polyethylene Backing - .015"/37mm Diameter, 68lb Test, Color White The touch and feel of Dacron combined with the strength of Gel Spun in a single 8 braid PE line for use in all fly fishing applications. How much Hatch Premium backing will you need - See Product Description below. Various lengths available wound from bulk spools of Hatch Premium Backing. You only have to buy what you need - enough to fill one reel or buy in bulk.