Berliners

 

These are Berliner Muehlenfeld handcuffs. They are very unique and rare, but they were made by several makers in the Berlin/Solingen area of Germany. There are maybe half a dozen pairs total that show up upon a quick search.

These sold on eBay for $5,426 after 13 bids. 

Here is another example that sold for $2,000 from oldhandcuffs.net at an unknown point in time. 

Here is a set that sold for an unknown price. 

These remind me somewhat of the Austrian Dollar Sign cuffs, in that the cuffs are directly connected with no chain, and they open in opposition to the other cuff. A double cuff for two hands vs one cuff per hand.