The Compara-dun is a simple, durable design that adds only three materials to the hook, floats reasonably well even in broken water, and fools even the toughest trout. The upright fan-wing design triggers strikes from fish feeding on mayfly duns, but because the 180-degree wing also extends an equal distance to each side, Compara-duns have a "footprint" similar to mayfly spinners, which float on the water with wings splayed to the side. This makes the Compara-dun an easy-to-see and effective spinner imitation.

CDC

Any way you look at it, CDC, Cul de Canard or Ducks Bum is a pretty fabulous fly tying material. Softly wispy, buoyant and subtle these feathers are tops in the creation of trout flies. I know of no other material which has the ability to float as well yet remain delicate and insect like.

 By the way, you do not need chemical substances to improve floatability – the best you can do is to dry the CDC fly with an AMADOU patch.

 Pro tied on premium Dai-Riki 320 dry fly hooks.