The XCM-STW-100 ambient probe detects the ambient temperature excluding the internal probe of all actuators belonging to the zone. The probe can be placed where the actuators of the XCM-ATW series are installed on heating bodies with access to the actuator itself difficult (e.g. heater covers, convectors, fan coils, radiant panels or floor, manifolds). Works with three alkaline stylus batteries (AA), included.