Good day The device can only be operated with batteries. I operate 8 additional thermometers in addition to the data logger. It is important to know: The normal batteries of the data logger and the additional thermometers will definitely last 2-3 years. With this minimal consumption, mains-powered devices are hardly more ecological.

There is only one type of external sensor, they are suitable for inside as well as outside. One external sensor is included with the main station.