Johns Manville JMCleanBond® SBS Base Flashing is a self-adhering, modified bitumen sheet incorporating the features of a polyester mat with a blend of SBS rubber, fire-retardant additives and high-quality asphalt. The modified asphalt is self-adhering and has an easy-to-peel, removable release plastic film on both sides of the sheet and the selvedge for ease of application. This elastomeric asphaltic blend has full recovery properties after 100% elongation and lends elasticity and flexibility to the sheet. It is designed for use as flashing in JMCleanBond roofing systems.