Originally Posted by ilovemusic
I am in a place where I cannot easily order or obtain RW3 Rockwool.
However, the local builders' merchant is selling 50mm Flexi Rockwool at a good price.
Have you looked at heating/airconditioning/ventilation/refrigeration suppliers? That is who carries RW3 and similar product. I could find no usefull data to judge the appropriateness of the product you linked.