Small, autonomous data logger with internal air pressure sensor (barometer). The measuring principle is based on the measurement of absolute pressure and the counter-calculation of the measured air pressure in the data logger. Highlights: Barometer in the data logger, 1- or 2-inch housing, plug-in pressure and temperature sensor, 433 MHz short-range radio interface, memory for 250,000 measurement series, batteries (lithium) can be replaced by the user, service life up to 10 years, optional connection options for meters and temperature measuring chains