Northring for First Class Windfahne

The adapter is used for the north alignment of a First Class Wind Direction Sensor.
 
The adapter is installed between mast and sensor. The adapter is aligned to north by means of a bearing tube. After alignment the wind direction sensor is mounted onto the adapter. A pin in the adapter and a north boring in the base of the wind direction sensor guarantee that the sensor is aligned to north. There is no re-alignment necessary with replacement of the sensor.