OSI Asphalt Flash flexible flashing is a rubberized asphalt backed, self-adhering membrane. This membrane is a laminate consisting of a high density polypropylene film and a removable release sheet that has been developed specifically for the QUAD® Window and Door System. It is efficient, easy to use and provides excellent moisture and air infiltration protection around windows. It can also be used to seal doors and similar gaps and openings. Asphalt Flash can be easily applied in horizontal and vertical applications and will adhere to most common building substrates including vinyl, wood and concrete.