The ESTER_X40_NO_ISM battery room thermostat is designed for wireless operation with an external radio transmission module. ESTER_X40_NO_ISM does not include a radio module. The thermostat is mounted in the selected room and is designed to maintain the set temperature in the room by sending a radio signal to the module connected to the main controller. The applied two-way radio communication allows the transmission of information from the main regulator to the thermostat about the regulator's alarm conditions and the external temperature value. The thermostat on the backlit LCD display shows information about the room temperature value, the selected operating mode, the current time and the date with simultaneous synchronisation of the clock with the main regulator.