Abstract: A product in the form of a cushioning device made from thermoplastic film containing crystalline material inflated to a relatively high pressure and sealed at the time of manufacture. The product maintains the internal inflatant pressure for long periods of time by employing a form of the diffusion pumping phenomenon of self-inflation in which the mobile gas is the gas components of air other than nitrogen. Improved and novel cushioning devices use new materials, for the film of the enclosure envelope which can selectively control the rate of diffusion pumping, thereby permitting a wider latitude flexibility and greater accuracy in the design of such new cushioning device, thus improving the performance and reducing cost of such devices while eliminating some of the disadvantages of the earlier products. It is possible to permanently inflate certain types of new devices using readily available gases such as nitrogen, or air in which case nitrogen forms the captive gas.