The Klinkhammer is the creation of Hans Van Klinken and may be fished for trout, grayling, char, smallmouth bass and bluegill anywhere in world mainly on rivers.
A dry fly, CDC is an abbreviation for Cul du Canard, the tiny feathers from a duck's preen gland, which are naturally waterproof. This adds to the flotation of the fly which sits well on the surface of the water.