4-pack Mini Hygrometer Thermometer Fahrenheit or Celsius Meter Digital LCD Monitor Indoor Room Round Humidity Temperature Gauge for Humidors Home Humidifiers Car Greenhouse Babyroom

I am a professional musician in a house full of musical instruments. This 4 pack was perfect for monitoring the humidity in all the rooms where violins/violas/cellos live. You can even put one in the case. They seem accurate enough for every day use and were inexpensive.

I don’t know how accurate these are but they do work. Humidity was reading at 40% when I installed these in my machine. After adding desiccant, it dropped to 10% so they do work in helping me to monitor when I need to change the desiccant.

All seem to show the correct temp, but one of the 4 shows a very different humidity, off by about 30% from the rest. I tossed that one. There is no calibration that I can see. Of course there are no instructions...

Like most people, as soon as I opened the box I put all 4 side by side, and sure enough the readings were very close. I took one of these out on our morning walk today and was very impressed by the speed of response on the humidity readout. As we walked up a hill the humidity went up from 72% to about 82%, which made sense as it was a bit Misty. When we walked into a building it immediately dropped to 65%, and it dropped to 45% when we put the a/c on in the car. The temperature display seems a bit slower to respond, but I was very impressed. These are nice and small to stick to the wall in different rooms, but the readout is easy to see. A good deal.

I bought several 10 packs of other brands that mostly looked identical but those were all off more than 20% humidity and way off temp too (yes 20%... room is 30% and others showed 50%!). If the screen has a green hue and the circuit board looks brown... better test them to see if they are accurate. The ones I tested with the green hue screen and brown or tanish boards were terrible.This brand is SPOT ON accurate and consistent. Screen has a gray hue. Usually +/- 1% humidity and +/- .2 degrees temp.. in short... ACCURATE! They also COME WITH EXTRA BATTERIES! OTHERS DO NOT!

These are cheap, and the temperature readings seem reasonably accurate. I think the humidity readings are okay for moderate to high values. But they're very inaccurate on the low end. None of the ones I've bought will read below 17% even if they're in a sealed, dry container full of silica desiccant beads.Physically, they're not super sturdy, but they're good enough. None of mine have fallen completely apart, but I've had a few whose cases started to come apart when I've pressed them into a 1 5/8" hole. I was able to press them back together just fine, and the clips have held them into the holes so far.Even with those problems, I'll continue to buy more to use in my 3d printer filament dry boxes. I just have to remember that a reading of 17-18% means "really dry", which is good enough for my purposes. I don't need the extra accuracy I'd get from a more expensive hygrometer.

Works well

As you can see the temperatures are off within about 1° but there's an outlier on the one with the humidity. They're cheap what can you expect? Thankfully I only need three.