Product review (3 stars): Right now it is useless. The manual says "Open battery compartment cover
I will update this review once I get a battery for the device. Right now it is useless. The manual says "Open battery compartment cover, take out the polarity insulator, and put on the cover, then the meter starts to work." So I open the battery cover--NO polarity insulator or battery. Had I known that I would either have purchased a different device or at least got a battery so I could use the one I got.

Update: I fortunately had the right button battery in my stash, so now the device is working. I'm updating the rating to 3 star since the device works as expected and only the missing battery is an issue.

One comment--It cycles between temperature and humidity. No way to change the cycle time.