||Manufacturing inspection approval (stamp of approval)
||Roman numeral 3, on bottom near pins
||Near pins on bottom
overall: 1 1/4 in x 4 in x 4 in
This is one of four rotors related to an ENIGMA encryption/decryption device, but does not match the serial number of B197.81 nor B198.81. Stamp of approval (inspection) marked with a Nazi swastika.
Per Ralph Simpson of the Cipher History Museum, "The 'A' indicates use by the German Army and Air Force (Navy used 'M' for marine)." [2016-05-09].