Modified Bitumens were developed in Europe in the 1970s when Europeans became concerned with the lower performance standards of roofing asphalt. Modifiers were added to replace the plasticizers that had been removed by advanced methods in the distillation process. SBS is used as a modifier for enhancing asphalt and provides a degree of flexibility much like rubber. It also is applied to a myriad of carriers and produced as a sheet-good in rolls that can be easily handled.