Maybe I'm alone on this, but the "material" tag is misleading, at least to me. When I hear the word "material" I think of metal, cloth, foam, etc. Things that make up something. When I hear "material" used in the acoustic sense, I think of foam, fiberglass... typical absorption stuff. To me this is a (series of) Helmholtz resonator rather than the traditional "material" (cloth, foam, etc). And I think, at least to some, that may be why there is the initial scoff... because the first thought I had was "Oh, sure, kef put some foam in their cabinets that is super great". But when you look in to what it actually is and find out, then it seems more plausible and not just some audiophoolery/marketing.