Glass wool

Insulating material made from fibers of glass

Glass wool

Glass wool is an insulating material made from glass fiber arranged using a binder into a texture similar to wool. The process traps many small pockets of air between the glass, and these small air pockets result in high thermal insulation properties. Glass wool is produced in rolls or slabs, with different thermal and mechanical properties.

From Wikipedia, under CC BY-SA. More on occurri.