BASEGARD SA Base Sheet consists of a Styrene-Butadiene-Styrene (SBS) rubber modified, self-adhesive asphalt blend reinforced with a 1.8 lb/1000 ft per square (90 gram per square m) glass fiber mat and coated with a fine mineral release agent on the top surface and an opaque release film on the bottom surface. BASEGARD SA Base Sheet can be used as a base layer or as an effective vapor retarder.