... as high impact resistance, good head good insulation, sound insulation, light weight, flame resistance , weather resistance, easy cutting ,good machining ... fire retardant guade B1 decided by the national GB8624_97 test,without fire duop nor poisonous gas. 5.impact resistance ... recognized wordwide for sound insulation on expressways. 7.portability light in weight,it is easy to handle and make drills , ...