Johns Manville DynaGrip® Base SD/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. The modified asphalt has an easy-to-peel and is self-adhering, removable release plastic film on the bottom of the sheet and selvage. It is designed for use in roofing systems where two or more plies of modified bitumen are desired. The top of the sheet is sand surfaced.