ELASTOPHENE Flam is composed of a proprietary formulation of elastomeric styrene-butadiene-styrene (SBS) polymer modified bitumen & is reinforced with a high quality random glass fiber mat. Elastophene Flam is a SBS-modified bitumen base ply for use in approved multi-ply membrane and flashing assemblies. The topside and underside are surfaced with polyolefin burn-off film to optimize heat welding.