Mallard Flank Feathers are truly versatile and have been used in patterns for decades. Harelines Mallard Flank is an excellent choice for things like tails and legs on nymphs, wings on wet flies, upright or down wings on dry flies, claws or shellbacks on crayfish, crabs, and shrimp, looped wing emergers, large soft hackles, wings on streamers, cut wingpads, and even some Spey and salmon flies.