Ordered a couple of these to help deal with the horrible echo in my ~2,5 x 5m. I wasn't expecting them to work wonders or anything, but wow, the reverb and "ring" in the mid to higher frequencies is almost entirely gone now!
These panels are quite large and thick, but still very easy to handle and hang (I used adhesive velcro). They are also a bit darker than they appear in the pictures.
For this price, I highly recommend these.