How about $ and where you bought it.Bought a tyre pressure monitor (Careud M3) from Aliexpress. First one came with a broken button, but I got a full refund after talking with the seller. So I ordered another one and this one worked fine. It's fairly accurate, compared to an analog gauge, and the battery life is fine (just had to load it up first time, two months after installing).
I haven't ridden with it in rain, but I have pressure-washed the bike (including the wheels and the central unit) and it still works. There's sometimes a bit of condensation visible on the back side of the LCD when the bike is taken out from a garage into bright sun but it goes away after a couple of minutes. The LCD itself is easily bright enough to be visible on a sunny day.
I've since bought another set for my second bike and it also works without issues, showing accurate pressures.
It also shows temperatures, it's fun to observe how much the temperature and pressure rises during a ride. Turns out, rear tyres heat up much quicker, the front one tends to stay much closer to ambient temperature during normal riding.
I can definitely recommend this farkle.