I have purchased several of these beauties.
They are really well made, a lovely colour and work amazingly well.
So much better at absorbing bass frequencies than your standard grey "acoustic" foam. I mean... a lot better!
They also look so much nicer in my studio and when you are working in that environment for hours and days at at time.. you want a nice wall to look at...well I do! No more crumbly grey foam, crudely glued to a wall, tuning green after a few months.
You can also dust these panels easily by taking them out the frames. Try doing that with glued on foam panels.
I recommend wholeheartedly Hofa absorbers for any one serious about sound and aesthetics in their studio.
I intend to buy more of these very soon to finish my studio.