FIG. 3 shows the preferred embodiment of the invention, a plastic tube coated with at least two layers of barrier materials. The preferred embodiment includes many components which are substantially identical to the components of FIGS. 1 and 2. Accordingly, similar components performing similar functions will be numbered identically to those components of FIGS. 1 and 2, except that suffix “a” will be used to identify those components in FIG. 3