Mini Digital Thermometer 2-Pack Hygrometer Indoor Humidity Monitor Temperature Humidity Gauge Meter with Fahrenheit (℉) for Humidors, Greenhouse, Garden, Cellar, Closet, Fridge Etc by DWEPTU

I use them in my snake tanks and they work well

I keep one in my backpack’s side pocket all the time and it’s perfect- right size and it works.

It's probably my fault for being too distracted by the low price to not notice the physical design of these before I bought them. The price is great, and so far they seem to work, AND they come with spare batteries, which is the best part, really.But the shape/design of them might not be best for use in humid terrariums. They clearly are built to be placed into an area that specifically fits them, so that they're almost flush with the wall, which, again, is something I should've noticed from the pictures first.They do come with a little section of adhesive to stick them to a wall, but that just doesn't work with their design, because the adhesive pad would completely cover the battery door.And the biggest reason I'm unsure about their use in a humid terrarium is because the casing isn't completely closed off and sealed; it has a few open spots along the sides and back, meaning that moisture could very easily get into the battery compartment and inner workings, and that's just not safe for anyone.So I still haven't used them inside my snakes' tanks yet, but they do seem to work just sitting in my room, and they both seem to be displaying the same numbers, though I can't guarantee the accuracy of them. And for the price, it's not bad at all; I just wouldn't recommend using them inside animal enclosures, just to be on the safe side.I will try to update this review with pictures when I get home.

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

Very small and they came with extra batteries and work good.

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,