Product review (4 stars): I like it so much I ordered another in white to put on my back porch the same day I received it. :^)
This review is for the "SUKRAGRAHA Mini Digital Temperature Humidity Meter Gauge Thermometer Hygrometer LCD Degree Fahrenheit (F) Display Black".

Edit (added on January 26, 2018): I lowered this from 5 to 4 stars as after receiving the second one and keeping them side-by-side in the same room for several days, they're always 1-2 degrees and 2% (humidity) off from each-other. So while they may respond fairly quickly, they're not extremely accurate. Still great for the price, though.

It's not obvious from the single picture, but this is designed to fit into a rectangular hole as it has tabs to hold it in place on the side and a flange around the front with the ventilation in the rear, so it will measure the temperature and humidity on the rear side of whatever you mount it on/in. This flange also helps it stand up on a slightly upward angle, in case you want to put it on a windowsill or something along those lines. It also came with a square of double-sided foam tape for additional mounting options.

The reasons I'm giving this 5 stars are: it has a very easy to read display with strong contrast and wide viewing angles; the body is very small for the (large) size of the characters in the display; it responds quite quickly (I'm watching the temperature and humidity adjust as I type this after removing it from a home-made 3D filament dryer); and the price is very nice. I just looked at the info sheet that came in the package and see that it updates the temperature and humidity every 10 seconds.

I bought this for a 3D filament dry-box that I'm making. I'll be using this on the inside of the box so I can monitor it to make sure the humidity levels are kept very low. I originally planned on viewing it through the translucent box, but I may just cut a hole to snap this into for improved visibility (and a better looking box).

When I first saw the package, I thought they sent me the wrong thing as it had a picture of a slightly different device with the label "Digital Thermometer". I was relieved to find that the hygrometer I ordered was actually inside the box.