Great idea, but the hygrometer is waaaay off (at least 20%) when checked against 2 others that agree. The thermometer seems accurate and it's a nice size.

Extremely lightweight and suspect low humidity readings - I live in Spokane and right now in February with outside humidity at 97% - and my apartment temps at 60 degrees - this thing is indicating which just cant be right. Looking into a Honeywell or Weatherchannel hydro - good reviews on Amazon

If you're looking for an accurate hygrometer to protect your instrument, keep looking... I tested 2 Planet Waves unites (purchased to monitor 2 martin guitars) and found that they both reported wild fluctuations in humidity over a 24 hour period. In my line of work, our environmental lab (used for testing electronics) has a quality hygrometer which recorded the set test area humidity (in a 24 hour period) between 48%-50%. Over the same period, in the same location, both Planet Waves units recorded readings between 31% - 52%. The Planet Waves units did not even agree with each other and recorded low humidity readings randomly over a 24 hour period as shown on each of the date/time memories. The test was repeated 3 times with similar results. Clearly these 2 Planet Waves units are not reliable and if representative of the design, should be avoided. As mentioned, it’s unclear if this is a design flaw or the result of something missed in quality control however it is clear that this defect would prompt the user to employ a humidifier product when it’s unnecessary.

My favorite thing is that it tells you at what time the highest and lowest humidity and temperatures where. I know what conditions my guitar is exposed to even when I'm not around.

Very easy to use and very sensitive. Don't go without one if you love your acoustic.