They were within 1% of each other. and within 2% of my other ones in the house. I would buy them again. Picture shows them dead on of each other.

Makes it really easy for me to determine whether it’s too cold or if they need more humidity. They work so well, temperature is helpful, super small, easy to attach with the double sided tape. I do wish it was backlit, as it’s super dim, but still helpful

With humidity and moisture issues after all the rains this past season, we were trying to have a better monitoring on the air quality in our home. These little digital meters are the perfect simplified answer. The price is right doe the perfect and basic quailty meter. The display screen is small but direct with the temperature and humidity level. These were all we needed to know. The battery life seems to be great so far but just in case they also send extra batteries as well just in case. We'll see how long these original one last.

These compact but easy to read little Thermometer/Hygrometers work great! Extra plus of having four extra batteries.

Picked these up to double check / verify humidity; stated was 61%, where 62% is optimal. Temp is similarly accurate. Great item to verify your humidity levels. Takes about 3min for the hygrometer to adjust by 1 degree, so give it a few minutes, once you've added to your jar.Devices arrive 'running' (batteries active), so hard to calculate initial battery life. But they supply spares, and the battery size is a standard one, so even if you have to replace every 6 mos... that's not too bad for peace of mind. Maybe get some Energizers, if you want to guard against CCC batteries leaking, down the line.If this thing conks out for anything besides batteries, will update this review. For now, this suits my herb storage perfectly. If it lasts a year, I'll have gotten good use out of it, IMO.

I'm not including a picture because the ones provided in the Amazon listing are perfect for this product. Planetary overheating causes rather minor variations in what is called dew point but those variations are associated with very large variations in comfort. Dew point is easy to compute using the figures provided by this meter which are accurate and easy to read. The product can be carried with you indoors or outdoors and is moderately water resistant. I intend to incorporate this product into a control panel which will hold my telephone my smartphone as well as this meter above the front derailleur mount on my tricycle. Most phones now have pressure meters but it's awkward and difficult to get readings of humidity from a phone. A good benchmark for comfort is a dew point of 65° Fahrenheit. A good benchmark for discomfort is a dew point of 70 degrees Fahrenheit. If you want to you can connect to the weather computers at weather.gov and navigate to the hourly weather predictions for your location. If you have a reliable internet connection and our mobile and need to be able to predict your comfort level such as I have a need for when I ride my tricycle then you can select in the hourly weather predictions from weather.gov the dew point for your location and track when it is above 70 at which point you probably won't want to go outside. But lacking a reliable always on internet connection on a mobile pedestrian human powered vehicle this meter provides the same information for the current status of the air using a relatively simple computation which you can find on the Wikipedia. I recommend this meter for any amateur scientist pedestrian who wants to know when comfort levels are approaching their tolerance limit and also for anyone who wants to place it near the thermostat in their home to provide a little extra information for adjusting the thermostat to maintain comfort instead of merely a temperature

The units seem good. May not be all matching values due to tolerance, but there is something I just started noticing as I'm getting deeper into using them, that worries me.I noticed when reducing humidity, that the unit jumps from 25% to 16% directly. At the crossing, I saw the display jumping back and forth between 25% and 16% until it stabilized on 16% as the humidity gets drawn out of my system (with desiccant bags). This observation gave me confidence in thinking that the unit is not capable of showing intermediate values, hence, this was the resolution it could provide (at those humidity levels). So how many steps does the humidity display has between 1% and 99%? just 8 steps? 5 steps? what values are they?This makes me concerned that at low humidity ranges, the resolution of this device may not be good enough for some applications. It makes me happy when I think that the unit may be potentially using a calibrated lookup table to report fairly accurate humidity values, but the lack of resolution (going from 16% to 25% with nothing in between) makes me worry about this resolution issue maybe getting even worse at lower humidity (does it have one more value (say 6%) and that's it? or is it going to stop at 16%? Time may tell for me, if my desiccant bags are able to further reduce humidity, but how to tell?)I believe these type of units (there seems to be many versions of this device, perhaps all with the same sensor/electronics guts inside) are in need of some analysis study that would let us, end users, know what to expect. I do not have the equipment to do such, and hope someone with interest would share a basic study, or maybe a link if it has been already done. I know that we get what we pay for, I just would like to improve a bit on the question: what did we paid for?Bottom line: How much money (and time) will we end up spending, to determine if we can rely on these units? I already know they don't quite work the way we 'assume' they will work (there is no claim on displayed resolution, reading step size, etc. so it's like a "what you see is what you get" kind of deal...)==============================6-Month Update:After about 6 months of use, I confirm the humidity reading at the low ranges is not more than a coarse circumstantial number, not to be taken literally.I confirmed this with other devices I bought that are more expensive, with BLE wireless connectivity, etc. Maybe these little low cost devices are more reliable for higher humidity values, but for low ranges, it can measure over 15% discrepancy (if it was an offset I could work with them, but the readings seem to be erratic around the actual humidity level). Depending on your use case, this could be OK, for example you just need to know if it is going over 30% and that's it. In that's the case this device may the job.For me, this is the end of the road with these little devices. I will keep on having them on my home AC vents, until the batteries die, but since my use case is low humidity for 3D printer filament, they do not help me much for my time invested in keeping the filaments dry. I am turning to 2x to 4x more expensive devices now. To keep my review true to my experience and in an effort to be as transparent as possible I now reluctantly reduced my rating from 4 to 3 stars (because at first I was happy with them), to reflect this 6-month experience.There is nothing wrong with them considering they sell as low as 99-cents each in large quantities. I believe it is impressive that people could buy such technology including housing, sensors, processor, LCD, and even batteries for the money. Incredible! I thought I could use them, and it turned out I can not. My sealing system deteriorates with time and need re-dehydration, and these particular low cost sensors will not let me determine when I need to re-dehydrate.(I aimed too low, and had to rethink my strategy).Hope this helps,