Perfect for homemade mustard, broth, and other reductions, as well as for homemade spreads and pestos. The classic, straightforward shape allows for many applications. The clear surface is excellent for labeling and can be easily marked with a sticker. The iconic twist-off lid indicates whether the canning process was successful, as the inwardly curved area shows the result. Ideally, you will hear the typical pop sound when the vacuum is released upon opening.