they are in fact foam panels in the midst of which passes a wooden broom, it's pretty simple construction, 9 boards, stand and wooden rods that pass in the middle of the foams
At the beginning, when i received them I was very disappointed and I almost send them back, because I was expecting a real wall, not foam that floats in the air, but actually it is great to use and very flexible, lightweight (easy to move around) and can be put anywhere. The ideal is to always put them up against a wall, it covers a large area and the absorbing foam is of good quality.
I bought them because the price had dropped from 60 euros, the positive aspect is really "I place where I want", when I use only 2 foams, I use the third elsewhere. On the other hand, in the middle of a room, as those are foams that hold in the air, they do not hold really tight together, the sound passes between the panels.
Against a wall, it absorbs well.
I use it now for 6 months.
My problem is that my rectangular room is too large and creates a not-so-nice reverb to mix etc ... With it I have no more problems. So for the price as an acoustic solution it is not bad at all ...
I use it of course to record vocals by placing the panels around the mic, it does not simulate a real vocal booth, but still helps out greatly! There are other solutions, but for a few hundred or thousand Euros ...