Scientific Anglers Specialty Tri-Colored Dacron Backing - Backing doesn’t just connect your fly line to your reel, it also provides insurance for those drag-blistering runs of steelhead or bonefish. It works hard. Now let it look good. Scientific Anglers Dacron backing offers a thin diameter, high abrasion resistance, and peace of mind, knowing that the fish of a lifetime won’t be getting away from you this time. Now available in six bold new colors. .