GAP Fiberglass #90 Mineral Surfaced Roll roofing felt is manufactured from fiberglass mat and is coated on both sides of the fiberglass mat with weathering grade asphalt and is covered on the top with ceramic mineral slate surface granules. GAP Fiberglass #90 Mineral Surfaced Roll is a general purpose economical choice roll roofing product that can be used with cold adhesives or hot mopping applications for low slope roofs.