This is a close cousin to fiberglass made from stone fiber. The material has been long used in Europe but difficult to find in the USA until now.
We have not made acoustical tests, but we can assume it has similar characteristics to fiberglass. While the rock wool has a gritty texture, it doesn't seem to irritate the skin like fiberglass. Although large sections won't sag, it crumbles easily and cannot be "fluffed" like fiberglass or wool.
It can be cut easily to fit with a sharp knife.
