LASTOBOND Shield HT (high temperature) is a SBS-modified bitumen underlayment for use in approved steep slope assemblies and is designed to withstand service temperatures up to 239°F (115°C). LASTOBOND Shield HT is composed of a proprietary formulation of elastomeric styrene-butadiene-styrene polymer modified bitumen in combination with high tack self-adhesive. The topside is surfaced with a high strength tri-laminate polyethylene film and the underside is surfaced with protective polyolefin release film that is removed during application.