Rockwool insulation looks and feels a lot like fiberglass, but is more resistant to moisture, mold and damage. Rockwool also has a higher R-Value than fiberglass. Additionally it's much less flammable.
Rockwool is also available as blankets, the batts come in various widths. Given that Rockwool is recyclable and environmentally friendly, it can be said that Rockwool transcends its origins as a by-product of steel production. The stuff we're talking about here is known as slag wool and it's something we're always eager to receive
Strong Resistance to Heat
Rockwool is the best fabric in terms of heat tolerance. You can't melt it below 2000 degrees. It resists mold and moisture damage and it doesn't soak up water or change the size, even if you cut it into smaller pieces.
They stay intact more than fiberglass, and create a warmer environment. Rockwool insulation is also much less expensive than other types of insulation that can be used in your home. However, Rockwool may not be available in the size you're looking for.