Hungarian River Police badge

The badge shown here is a very rare badge of the Hungarian River Police (folyam rendőrség) from the Horthy (1920-1945) period. So far research has not resulted in additional info but I did get one photo where the badge can be seen. It was worn on the left sleeve.

Officer of the Hungarian River Police (WW1 veteran) with the same badge.

Do you know more?

I am looking for additional info. If you know more please let me know so I can update the blog. What period was the badge used exactly? Was it for all ranks? What quantities of the River Police did exist?