I found it to be very good quality and packaging. It doesn't seem easy to break. Its temperature matches the reading on the aquarium thermometer. Very economical, so I am very satisfied.

I bought 2 of these thermostats and I use them in water containers of the same volume (~20L), under stirring. I wanted them to keep the water at 24-25C. Even in larger containers (50L), neither of the 2 thermostats heats the water properly. After a lot of effort, I managed to find the ideal settings. One had to be set to 27C to keep it at 24-25, while the other had to be set to 29-30C.