They are a continuous mineral wool carpet, stitched by high -strength glassons. A metal grid, aluminum foil or fiberglass or without lining can be used as a makeup material. The main densities correspond to GOST 21880-2011, namely MP 50, MP 75, MP 100, MP 125. The thickness of the material varies .. Details: https://www.baswool.ru/catalog/maty-proshivnye/