The C.L. Morgan Co., where I got the small amber glass vials to repackage Potable Aqua for my mini-PSK, also offers a "sample pack" of their various sizes of zipper top plastic bags for $2. They included that with my order, and the smaller ones have proven very useful for segregating or waterproofing various bits of my mini- and large PSKs. Here is a link to their ordering page: CL Morgan .