Montana Fly Company Speckled Double Bead Stone - Peacock (3-Pack)

Affectionately known as the Cheeseburger nymph, this heavily weighted fly is a fantastic stonefly nymph.  

With its peacock herl body and peacock sword tail, this fly looks alive in the water.  It's often used in a two-fly rig with a smaller (and lighter) fly hanging off the bend of the hook.