DuraFlex G4FR SBS is a fire-resistant, premium SBS (Styrene-Butadiene-Styrene) mop or cold applied membrane with a high reflective white granule. Manufactured with a fiberglass mat that is saturated and coated with high quality, asphaltic bitumen and SBS elastomers for a durable, flexible and easily maintainable membrane. It is designed for use as a cap sheet in modified bitumen and hybrid built-up roof systems.