Most anglers don’t often think about fly line backing until they see it – and when that happens, it usually means they are connected to a big fish. Fly line backing is used to attach a fly line to a fly reel. The length and breaking strength of the backing that you use depends on the capacity of your reel and the type of species you are targeting. Backing serves two primary purposes. The first is to create a larger diameter spooling surface so your fly line fills the entire fly reel. The second purpose for backing is to provide additional running line for hard fighting fish that make long and powerful runs. Having the right amount and type of backing for the right reel can make the difference between losing and landing a fish of a lifetime.