Today I got some mylar bags that have a ziplock closure on them. They're 5" x 7", and the idea is that the rip notch is right under where you seal- you open the bag and can re-seal it with the ziplock. They seem to seal very well. They're 5 mil thick and seem very durable. And they're more flexible than the retort pouches. If they're durable enough I'll probably explore them further. A more flexible bag allows the package to be sealer smaller.