Fero 51
From Night Vision Wiki
The Fero 51 is a device of west German origin. It is a Gen. 0 bi-ocular utilizing Telefunken 6914 tubes. The housing utilizes 1.5 volt batteries and has exchangeable high voltage cartridges.[1] It is a bi-ocular device with a distinctive long objective lens that protrudes from the housing. It is distinct from the later D51 model, with no commonality between the two.
The device is the predecessor of the Fero 52 (1).