This is a case of 6 pieces of Owens Corning 703 rigid fiberglass board in 24 x 48 x 1 inch pieces.
Click for Owens Corning 703 1 in. single pieces.
For an identical product at a lower price, check out ATS Acoustics Rigid Fiberglass Board 1 Inch.
Mark's blog: Aardsma -On Life and Business