These Oiler Puffs also known as CDC Puffs are great for emergers and dry flies. These short, extremely fluffy feathers lack discernible stems. Especially ideal for smaller dry and emerger patterns. Cul de Canard Feathers also referred to as CDC Feathers are one of the greatest natural fly tying materials available. The unique structure of the feather makes them extremely buoyant. The movement of the individual fibers is lifelike and draws the attention of trout. While Cul de Canard is primarily used in dry flies and emergers, it can be great when used for soft hackles and legs on nymph patterns.