USP® APP 160S is a tough smooth surfaced, APP (Atactic Polypropylene) torch applied membrane. Manufactured with a non-woven polyester mat, that is saturated and coated with high quality, non-blown asphaltic bitumen and APP resins for a durable, heat resistant, flexible and easily maintainable membrane. It is designed or use as a base, inter-ply or cap membrane in modified bitumen roof systems.