This basic closure system both is economical and versatile. You can convert any bag to a reusable storage bag by just pressingdown and matching the tracks together.
For granular or powdery products, you can put a two-track zipper that has an additional track for extra protection. Often, small particles can get caught in the zipper making the bag difficult to close. Having a two-track zipper allows the bag to close with the one track if the other path is clogged up.