Link for acoustical treatments

Has anybody tried anything like this?

I was wondering where I would put these in a room? And if there would be a difference, what would it be? Seems like a very cheap way to improve sound, but usually there is a catch to such modestly priced "upgrades".
The actual effectiveness of foam is very low, try checking out some sites like ATS acoustics or GIK acoustics, these are made from mineral wool and fiberglass sound absorbers, and tend to work much better for not much more $$, plus they are fabrid covered and look much better.
Foam is only useful for the highest frequencies. Higher density materials are broader band absorbers. For bass below 200 Hz, panels or resonators are most effective.