RIO Fly Line Backing, DACRON, 20 lb Test, WHITE - 100, 150, 200, 250, 300, 400, 600 up to 5000 yds RIOs traditional Dacron braided backing features high strength and low stretch and is unsurpassed in quality. Good compromise between thinness and the ability to make blind splice loops Easier to knot than brands that are very thin but have too tight a weave for a blind splice loop Various lengths available wound from bulk spools of Rio Dacron Backing. You only have to buy what you need - enough to fill one reel or buy in bulk.