12 Pack Pgzsy Mini Small Digital Electronic Temperature Humidity Meters Gauge Indoor Thermometer Hygrometer LCD Display Fahrenheit (℉) for Humidors, Greenhouse, Garden

Exactly what I was looking for.I wanted a simple way to check the humidity of my 3d filament that I store in vacuum bags.I printed a holder and the rest is history.All of the monitors were within 1% of each other and passed a salt water humidity sealed test.I especially like that it uses a standard cell battery that I have a lot of.Thank you. 😊

At about $1 each, a nice bargain. I put these in cereal boxes to store 3D printing filament with desiccant. They all seem to work. I've ordered 4 more to use with all my filament storage boxes.

I planned on pitching the least accurate because of how cheap they are and I am highly impressed for the price. I’m using these for curing cannabis. I haven’t tried calibrating anything. I will update the review based on my ACI controllers readings compared to these if they are way off. They have been on my kitchen table for a couple hours acclimating from delivery. As others have said they come turned on, but you can buy the batteries cheap.

Bought the 12 pack. RH readings varied by ~7% out of the package except for one hygrometer that never changed from 20%, even after swapping out batteries. After setting remaining hygrometers out for a day, they actually all read within 2% of each other and seem to be pretty sensitive as some would change just by having my hand close to them. I'll give it 5 stars due to price/value even though one was trash out of the box.

Seller was fast at getting the item to me. Item did have what appeared to be water damage staining on the box, but was not wet or deformed at the time of delivery, and the internal parts showed no obvious damage. I believe the packaging was wet at some point in the warehouse storage from FBA Warehouse, or the Manufacturer's storage.I use these hygrometers, as many others do, in 3D printing filament storage. When storing filament, the difference between 25% humidity and 35% humidity is the difference between needing to put your filament thru an 8 hour drying process and delaying printing of your model by that much time. So, if a sensor is wrong it could cost me a whole day of production, and possibly wind up irritating the customer that shipment of their anticipated item wasn't shipped out quickly.The numbers are large and readable. The temperature and humidity readings are quite quick to change - They update every 1-2 seconds. The issue that I have with these items are two-fold.1. They aren't accurate to the actual humidity percentage -- and I'm not just saying that, I did several tests to confirm before choosing to not keep these as a reliable instrument in monitoring my storage solutions.2. One of them repeatedly turned off when shaken or moved. Not sure how or why, but that's not a great sign! Once it was tapped gently on the table or given a soft shake, it would come right back on, which tells me it's not a battery voltage issue.Some of the readings weren't even close. Even between themselves, as a whole pack of 12, these sensors were showing a high degree of variance from one to the next. It wasn't anything crazy like 20% off, but it was 2-8% of variance between the lowest reading and the highest reading, while sitting within 18 inches of each other.I said I tested these in several ways, so i'll tell you now HOW --Between taking photos for each test the item was allowed to sit in the environment for several hours to ensure that it wasn't reading something absurd like a fairly moist gust of air from a cough or something silly. No - these were tested in a manner that would be scientific. All within a reasonable distance of each other, in the same room, and in a room that had active air flow and no external factors like a pool, faucet, toilet, sink, or anything silly to throw off the readings.I have a hygrometer from another brand which reads several humidity points lower than the product that I received listed here. So, since they don't match up within 1-2% of each other, this product has failed that test.Next, I decided to put it against my Marathon Atomic Clock which has temperature and humidity sensors built in. The item listed here would show the temperature to be the same but the humidity reading was way off. So, it failed that test.I have an AMS with my 3D printer, which cost several hundred dollars; I trust the sensor in it WAY more than I do this little 10 cent sensor. I let them sit in this AMS box, which is a weather-sealed containment unit, meant to keep filament dry with the aid of desiccant media that absorbs moisture. They sat in the AMS unit for at least 8 hours before I took the photos you see. The AMS sensor would show 17%, while the on-screen display for this item was showing 20%. So, it failed that test. While it's not terribly inaccurate in that case, it showed a decent amount of variance that I wasn't too happy with it. If it wasn't for the other testing I had done, and the power reliability issue I have with a few, I would call that "good enough" to keep them.Lastly, I placed all the sensors in a bag a moisture-absorbing desiccant media, thinking that maybe (as a long shot) some of the sensors could be clouded by residual moisture inside their plastic clam-shell housing, for whatever reason. These things get manufactured in a place where it's known to be quite humid, and then shipped across the ocean... I wanted to give these every opportunity to succeed. If that meant spending a few hours letting them sit off to the side, in an effort to balance them to the environment, i was going to do it. I let them rest surrounded by moisture-absorbing beads for at least 4 hours. When I removed them, they were doing slightly better, but still not great. Immediately after removal they started reading the ambient air readings, which is good for me to see in terms of sensor responsiveness to air quality changes, but the readings were slightly off and varied across the 12 units i had, so it wasn't accurate. Fast but not accurate means nothing when I'm looking for the true number of the room. I don't care if it re-takes the reading only 1 time every 2 minutes or 1 time every 2 seconds. I need the reading to be accurate - and these were not.The value per unit is there, but you sacrifice quality to get more of an unreliable item. I would move on to another brand, if you actually care about getting a valid reading from your equipment.

Works as advertised 👍

These are not accurate enough to cure cannabis. As soon as I pulled them out of the package I let them sit for an hour and took a picture of thenm and then let them sit for another 4 hours and took another picture. They vary up to 6 percent in both directions. The fact that my GEOVEE and VIVOSUN GROW HUB sensors read 41 percent humidity in my house when these ones are reading anywhere from 46 up to 52 is a whole different story of calibration issues I won't get into. But if you are trying to put these in jars with freshly harvested flower so you can cure it, it's not accurate enough to do that. You MUST keep your RH between 58 and 62 percent when curing. And if it's reading 62 but it's really 68, you're going to get mold.TRY GROVE BAGS OR BOVEDA TWO WAY HUMIDITY PACKS. Way more reliable than these. You can order grove bags directly from their website with a 24 hr processing time for a fraction of the price on Amazon. If you arent familiar with GROVE BAGS, do a little research. I work at a commercial cannabis greenhouse and it is industry standard now to package everything in Grove bags.It is essentially a bunch of breathable layers of polymer plastic so it works like a two way humidity pack in and of itself. Once you put the cannabis in the bag it will cure it and continue to cure it as long as it is in the bag. No burping. It keeps your flower right at 60 percent humidity and prevents it from over drying, getting mold and keeps the trichomes on the buds enhancing the terpenes, I.E. the flavor. And cannabis is like fine wine, the longer it cures, the better it is. So why not buy some bags that cure your flower continuously while you store it.Sorry Amazon I love your services and buy alot of your products. But sometimes you aren't the answer. I am returning this product.

They work, wish they'd ship with battery out of it.