Sonic discs are really excellent. They give an incredible amount of life to the flies.

With a sonic disc mounted, your flies really move a lot of water. At the same time, they cast much better than with a disc mounted loosely hanging on the leader. This makes it easier to fish effortlessly with even very large flies, which is a clear advantage along the river.

This version is made of metal and also gives some weight to the flies so they can fish deeper.

Below is a video for tying Bjarnes Tysker with a Sonic Disc: