Late and rare Kriegsmarine award.
Introduced on 15 May 1944 in bronze and on 24 November 1944 in silver has never had a gold variant. Awarded to U-Boot crew member who already had earned U-Boot War Badge, but without clear criteria. Be it number of missions, their difficulty or personal bravery. Receipient had to be approved by Karl Dönitz himself.
As for most certificates it can come to you blank or filled out (signed, stamped and filled out on a German period typewriter).