For installation under new shingles to prevent leaks from ice build-up and wind-driven rain. Also for use under shakes or metal roofing. Asphalt composition fortified with rubber (SBS). Flexible and elastic at low temperatures. Top surface coated with sand to provide a safe, non-slip working area. Split-back release film, self-adhering, easy to apply, easy to cut to size. Self-sealing around nails. Will not rot or decompose. Meets ASTM D1970; U.L. Class A and C fire rating.