The photometer function does not work. The pH measurement function is questionable anyway in such cheap instruments. I have doubts about the accuracy of the hygrometer as well, but I will compare it with other meters.

Waste of money. 2 out of 3 functions confirmed not working.

Hygrometer: In a watered plant, it shows DRY, no matter how deep I insert the instrument. Even under the faucet, it kept showing DRY.

Light meter: It shows DARK wherever you place it. The only way to get it to about halfway is to take it outside on the balcony and directly face the sun. For indoor plants, forget about it. Even in front of a flashlight, the reading stayed in the middle. I had to stick the flashlight directly on the instrument's eye for it to go to LIGHT.

Oximeter: I don't have test strips to test it. But judging from the rest...

The measurements of the photometer and the hygrometer are very good. I tested it in various locations. Now, as for the pH measurements, I'm not sure because you need to do a test to know if the measurements coincide

For humidity in plants that I use it seems reliable. It is a tool to check the soil moisture and its measurements are approximately correct.

It does its job at a good price. Minus 1 star for the build quality, it could be a little better.