Troutline Ultra Select CDC- Cul de Canard- These CDC feathers come from all different types of ducks who happily eat grass and swim all day in lakes within small local Bio duck farms. This is the reason why Trout Line provides the best quality feathers. They are all hand selected and hand dyed using the cold dye dyeing process as to not destroy the beautiful structure of the CDC feathers. CDC feathers, known also as Cul de Canard, are collected around the oil gland of the duck (wild or domestic bird ). It does not mean that oily aspect is the main factor of floatability. The first reason these feathers float so well is their special structure, the multitude of fibers and density. You don't need chemical substances to improve floatability. The best you can do is to dry the CDC fly with an AMADOU patch. 50 super ultra selected feathers per bag. Hand selected, hand dyed and hand dried in Romania.