Johns Manville DynaGrip® Base SA/SA is a self-adhering modified bitumen sheet incorporating the features of a medium weight fiber glass mat with a blend of SBS rubber and high quality asphalt. It is designed for use in roofing systems where two or more plies of modified bitumen are desired. The modified asphalt is self-adhering and has an easy-to-peel, removable release plastic film on both sides of the sheet and selvage for ease of application.