These are awesome little containers. We use them for holding sauces and dips for Bento boxes. We had to keep their lids on them, though, to help them loosen up. They're actually so tight it's hard to get the lids on and off. Having used them a while now, the lids are not quite so crazily tight. However, tight is a good thing, which is why we bought these over the eco-friendly metal containers. We value them not leaking EVER no matter what they are put through.