The Klinkhammer Trout Flies were invented by The Dutch angler Hans Van Klinken as an emerging caddis pattern to catch Grayling as they floated in the surface film and called it The Klinkhammer .However the flies can also be successfully used for other emerging nymphs. Hans also fished many of the rivers in Scandinavia as well as in his native Holland. His mentor was a Swedish fly fisher, Kenneth Bostrom who had created a fly called the Rackelhammer to imitate hatching sedge. It floated when cast upstream but Hans found if it was tweaked, to suggest life, it sank. Hans adapted the idea and made the Klinkhammer flies a fly that still floated after it had been tweaked. It became known as the 'Klinkhammer Special' . At first he bent the hook of a parachute fly so that the abdomen would sink below the surface and the thorax would float. Later he developed a special hook that did the same but imitated the curved body angle of the insect as it hangs below the surface just as it starts to emerge. This is what makes flies different from a regular parachute dry fly. The abdomen serves as a primary trigger, penetrating the surface film and getting noticed by trout from a great distance, well before they pick up on the above surface footprint features.