With a diameter of 6.7cm and a height of 7.8cm, our hygrometer stash jar fits perfectly into the Large Bzz Box. It comes with a sealable bamboo lid with a built-in hygrometer, for keeping track of the humidity in the jar. Ideal humidity for herbs is between 58 and 62%. When a two-way humidity pack expires, the humidity will fall outside of the desired range. By monitoring humidity you are ensuring the quality of your herbs.