Keep a watchful eye on your expensive dried goods with a Hygrometer Lid for your mason jars.
Now you can accurately* and easily see the humidity of any product you're storing. When used in conjunction with humidity control packages, keep your product fresh for extended periods of time.
The re-usable, one-piece lid eliminates the hassles associated with standard two piece Mason Jar lids. A Plastisol seal is permanently bonded to the underside of the lid and provides a far superior seal to that of any standard canning lid. It's also easier than lids that use totally separate seal rings