HOFA Diffusor natural

I bought the set that Thomann offers, 2 of these diffusors and a rectangular frame. The craftsmanship is borderline a joke, the diffusors are flimsy and cheap, and the frame was crooked. I had to seriously redesign the whole thing, drill new holes, dismantle the back and remove the excessive plywood, zip-tie the 2 modules together, and use padding foam to make the diffusors sit snuggly in the frame (they’re significantly smaller). If that cost 100 euros I’d understand, for 300 that’s absurd.
If you’re willing to go through all of that, the diffusors work, I do see some difference in my control room regarding persistent frequencies around 700-2K.