Bought two of those stands to raise my KRK Rokit 5 speakers to ear level, instead of having them lying on the desk. They provide good isolation from the bass frequencies vibrations, and can support a lot of weight. The build quality is not the best, especially the crumbling rubber that holds the frames and legs together. With that being said, they do their job pretty well and I find their design quite pleasing on my desk.
Pros: there aren't many alternatives on the market, especially at this price. You can adjust the "area" of the frame by screwing the big cogs on upper and lower frames. You can choose between two fixed heights.
Cons: although stable, they are very wobbly if you bump the desk. I think they overdid with the springs inserted in the legs. Build quality is reasonable for the price but not great.