£12 that’s very cheap
FWIW I have 1x Devolo (Was my first TRV) which is really good at keeping temp (The variation is very small) but was an absolute PITA to get included and installed. Like hours and lots of cursing. It also feels a little less physically robust than I feel it should. It does report back temp, so not a complete
I also have about 4x Eurotronics Spiritz TRV’s. They feel better built. Way easier to access the battery compartment, the display is clearer, controls are better. It also reports back temp. And was way easier to include.