If it one thing I could say about these containers, is that it would take a long time for something to perish inside. These appear to be extremely airtight. One thing I really like about these is that they are lighter and thinner than other pyrex dishes that I have, which makes them less cumbersome. The only downfall is the four snaps that you have to make in order to close the lid. I have a set of competitor containers, in which you only have to snap down two sides. Having to snap down four sides is a bit of a pain, but worth it if you are looking to maximize your food’s shelf life.