The Scientific Anglers Dacron Backing is engineered to serve as a dependable, high-capacity foundation when blistering runs strip your fly line down to the arbor and put your reel’s drag to the ultimate test. Constructed from premium braided Dacron polyester filaments, this backing features a tight, uniform round weave designed to pack densely and evenly on both standard and large-arbor fly reels. Its structurally stable round cross-section resists flattening under heavy drag pressure, preventing the line from burying or cutting into underlying coils during violent surges—eliminating the binding and sudden break-offs that occur when backing jams on the spool.