Roxul Rockboard Acoustic Mineral Wool 60 - 6lbs.pcf 48"x24"x1" 12pcs Mineral Wool Insulation in 6 pounds per cubic foot density. Great as Acoustic insulation or as a soundproofing material Very High NRC Rating, better than Owens Corning 703 Water repelling - hydrophobic- Class A fire rating Perfect for making acoustic panels and bass traps