Das Flottenkriegsabzeichen

The High Seas Fleet Badge (German: Das Flottenkriegsabzeichen), also known as High Seas Fleet War Badge, was a World War II German military decoration awarded for service to the crews of the Kriegsmarine High Seas Fleet, mainly of the battleships and cruisers, but also those ships that supported them operationally for which there was no other award given. Although the award was instituted in April 1941, it could be awarded for actions that took place prior to this date. It was "primarily in recognition of the sea struggle" against the British fleet.

Known makers: 

Adolf Bock (who also designed the award) 
Schwerin 
Friedrich Orth 
RSS 

These badges can be found made of two materials, Tombak or Zinc. Here is a list coutsey of by John Robinson: 

TOMBAK 
Schwerin Berlin 

ZINC 
RSS (version 1) 
RSS (version 2) 
RSS (version 3) 
RSS (version 4) 
FO soldered fittings 
FO cast-in fittings 
RS 
L/18 or 26 (Mayer) 
Schwerin Berlin 
L/21 

UNMARKED
L/21 type (Type with the deep indentation from the hull on the reverse) 

UNKNOWN IF PERIOD OR NOT
AS