the outer of the dunnage bags is made of high intension kraft paper ,pp woven and PE membrance ,which is tough and strong, it is inner bag is made of layers coextrusion PE film. the especially designed non- leaking air intake valve, which cna nedure more than 10tons of pressure,releases air inside the bag fast and easily. dunnage bag is easy to use, which is widely used because it may save lots of loading time and reduce transporttaion cost.