Although I have some remarks, 5 stars because it does what it promises! The connection method is a bit strange, with a removable power plug but with an automatic terminal - socket for its output. You need to know a little about connections to set it up. It can be connected in parallel with the existing thermostat (obviously it will be placed in another room) or it can replace it. The receiver - relay hangs directly on the wall but all the connections are on the bottom side and not at the back. The app immediately recognized the device just fine. The wifi connection works if connected via USB to any 5v power supply. The connection cable is provided but not the power supply. The wifi has a good range. The device is user-friendly. It has a differential setting (important) and a temperature adjustment setting, so if you have a better thermometer you can use it for calibration. It has open window detection with heating interruption and maximum - minimum setting. All settings can also be made from the app but with the thermostat off.

I bought this because I wanted to have the relay of the commands in the old spot and the thermostat in the living room.
I am attaching the connection to the previous thermostat, which was not wifi, and we can see two cables that are for the commands.
In general, it takes a lot of effort to connect it and all the cables are external. I didn't take a photo because I was in a hurry.
I pulled a 220V supply to power the transmitter and connected the command (for natural gas it is dry contact, connected to N and NO)
Then I paired the thermostat and after I connected it to the application and to WIFI using the USB.
Overall, the installation should be done by someone with electrical knowledge or expertise.
The user instructions are very lacking and quite confusing. I had read the previous comments but I wanted it because of the wireless connection and receiver so that you can have an indication from another room.
In general, unless necessary, it is best to avoid it.

The presentation of the product is misleading. In the description, it states: "It is powered by batteries and without cables, so it can easily replace your old thermostat." This is not true. Without a connection to 220V, the transmitter does not work, and without a 5V power supply, the receiver only connects to the transmitter via RF - it does not connect to the network.

I consider it a problem that the connections are not located at the back but at the bottom (see photo), so according to the manufacturer's logic, the cables should be exposed outside. Fortunately, the transmitter is relatively spacious, so I came up with a solution: I cut the cover, soldered 3 cables (one for common + L bridged, one for N, and one for the NO contact), and it worked fine.

Through the Internet, you can only do basic things (temperature adjustment and weekly programming). You cannot change the thermostat's settings, nor does it have statistics. Also, although Google Home recognizes it, I couldn't install it.

The room temperature measurement, tested with 3 different digital thermometers, is quite accurate. Pay attention to the temperature sensor: it is exposed outside the device and can easily be damaged.

Finally, the documentation is almost non-existent. Only a six-page document, which is doubtful if you can install it without experience with similar devices.

1 star for the logic of having the connections on the thermostat not located at the back but at the bottom, with the cables exposed on the outside. It's all over the place and still not connected, so I don't even know if it works