This is a case of 6 pieces of Roxul 24 x 48 x 2 inch AFB mineral wool. AFB stands for Acoustical Fire Batts. It is mineral wool at a density of 2.5 pounds per cubic foot. Higher densities absorb sound only slightly better than at 2.5 pcf but cost a lot more, which makes 2.5 pcf the most cost-effective density for absorbing sound. AFB is flexible, like dense household insulation batts. It does not hold it's shape like rigid fiberglass board (such as Roxul Rockboard 60). AFB is suitable for acoustic insulation inside walls, building into panels, or any place where there is a frame or structure to support it. PRODUCT SAFETY INFORMATION - Warning: Can cause respiratory, skin and eye irritation. Precautionary Measures: Avoid breathing fiberglass dust and contact with eyes or skin. Wear long-sleeved, loose fitting clothing, gloves and breathing and eye protection.