The TRV powered by of AA batteries to interlink with external slim wall Mounted Sensor (RS) to monitor and maintained the precise indoor air temperature even your radiators have a radiator cover or behind the sofas, furniture or any heavy curtains. One room sensor (RM) can also control up to 4 Radiators (TRV’s) where one or more Radiators are installed in a same room or in the hall. The TRV+RS is required Tuya Zigbee wireless hub to connect the valve and sensor to control through Alexa , Google assistance.