Blazon: Kürsch on a pale argent three ermine tails sable
These arms originally belonged to the Counts of Bregenz, a branch of the Udalrichinger family, who were allegedly descended from Charlemagne’s brother-in-law. The family later intermarried with the Counts of Montfort. In 1451, the territory of Bregenz was sold to the Habsburgs, and they added “Counts of Bregenz” to their considerable list of titles.
This is an excellent example of the heraldic fur Kürsch. This is used exclusively in Germanic heraldry. It is sometimes blazoned in English as “fur,” and does not have any set tincture; it is assumed to be proper. I have used the German word to avoid confusion with the more general category of “fur.”