Those look very similar to the VOCALBOOTHTOGO products that I linked, with the same aim at managing echo / reverb. Priced about the same too.
My lower frequencies are pretty good so I don't need bass control. And I don't need to control sound entering or leaving the room. I'm only interested in dealing with echo / reverb from that big wall of windows. If further reverb control is needed after treating windows, I'll build acoustic panels for walls.