"...a blend of recycled cellulose, paper and cotton. This material has extremely comparable sound absorption at mid to high frequencies and superior absorption at low frequencies, when compare with traditional fiberglass based cores."

http://www.acoustimac.com/acoustic-insulation-materials/acoustic-insulation/eco-core-acoustic-insulation

I have a chance to buy some of these used at a good price. Wondering if I should snatch them rather than building my own with Roxul.