1" x 48" x 24" Mineral Wool/Foil Backing High Temperature Insulation, Density 8#, Green - 40260 Pack of 2

Good product. We have a very drafty chimney and needed something that could handle heat from the wood stove but block cold air. This is perfect.

Boxes take quite a beating somewhere before getting to someone's door...or at least it did in my particular case. Was still usable but roughed up a bit especially for the price.