Today I received my Wing slider from edelkrone. It comes nicely wrapped in a pretty box and it has a good weight. It feels very stable.
You should be aware that the span for smooth movements is a little less than 4 times its width. But for minimal slider movements, this can still be nice. I recommend to use it with a camera with image stabilization. In my setup I filmed myself with a Sony a7RII and had a Sony A6300 mounted to the wing. So there is no stabilization in my test clip.
Manual movement can be sideways or dolly style towards/away from the object. It is lovely to see how the camera stays on the same level while the wing unfolds. The friction can be changed using the rotating wheel underneath. This works like a charm.
More about the product here: https://www.edelkrone.com/eu/p/187/wing