Great imitation for a Dun, and works well in slow water. CDC offered excellent air trapping qualities that results in tremendous float-ability
A fly-fishing DUN is the stage of the mayfly between a nymph and adult mayfly. The technical term is the SUBIMAGIO stage. This is a vulnerable phase for the mayfly since the wings are formed, but have a dull opaque color. Often this stage results in trout actively feeding from the water surface.