On their site, the specs say that for a 3" piece, at 125 Hz it's coefficient is 0.78. That seems to be the highest I've found at that frequency/thickness. http://www.roxul.com/graphics/RX-NA/...d60-8-7-07.pdf
Should I take a look at anything else or is this Rockboard 60 my best bet? I'm going to be doubling these up so that they're 6". My room currently has some pretty nasty stuff going on even under 100 Hz so I want to tame everything as far down as possible. I plan to put up foam around the room too, so HFs are not a concern right now.
I live in Canada, so 703/705 is not easily available but the Roxul stuff is (and it seems just as good or better actually). Price is not an issue (within reason!) and neither is weight. Thanks!