You cannot hold a humidity level you are not measuring. These are the small round gauges that sit inside a jar and read temperature and relative humidity through the glass — six of them, so every container you care about gets one instead of you moving a single meter around and guessing about the rest.
From our own use
We keep these in our jars to watch the conditions inside them. It is the only way to know whether a humidity pack is actually doing its job.
-
1.89 in across and 1.13 in tall — drops into a wide-mouth mason jar and still reads from outside
- Reads humidity from 10% to 99% RH, accurate to about ±3%
- Reads temperature from -58°F to 158°F, accurate to about ±2°F — this is the Fahrenheit model
- Refreshes every 10 seconds
- Runs on two LR44 button cells per unit — the same cell a watch uses — already installed
- Six units in the pack
Why we picked it: this is the cheapest thing in the shop that changes how you store. Put one in a jar next to a 62% pack and you will find out within a day whether your container actually seals — most do not, and until you measure it you have no way of knowing.
