The upper as well as the lower adjustment ring follow the same principle: if you want to adjust the lamp, the rings are tilted slightly, then they can be moved gently.
The inherent cable tension evoked by the fiberglass rod ´pulls´ the rings into a ´brake´, so they keep their position on the rod.

By sliding the two adjustment rings at top and bottom, the fiberglass rod is bent into the desired position, and the light is directed where needed. The cable tightens the rod into an arc, of which the radius can be varied as required using the adjustment rings. The fine adjustment is done with the swiveling lampshade.