A flexible blanket-type thermal insulation, commonly used as insulation between studs or joists in frame construction; also used as an acoustical material or a component in sound-insulating construction. Usually made from rock, slag, or glass fibers. Sometimes has a vapor barrier on one side or is entirely enclosed in paper with a vapor barrier on one side. Nominally 16 (40.6 cm) or 24 in. (61 cm) wide, and approx. 1 to 6 in. (2.5 to 15 cm) thick.