I was a little dubious that this would work in the real cold, and about its range through walls, but it works great. This might be because I used premium Li batteries in the remove sensor. It has been -30 C for quite a few mights lately and this thermometer has not had a problem. With regard to range, the thermometer is about 35' from the base unit and the signal must go through through an outside wall and a garage wall. No problem even on the cold nights. Be aware that this unit displays a 12-hour clock and Fahrenheit, or a 24-hour clock and Celsius. Since I prefer the 24 hour clock and Celsius, that was fine for me.