CASE  .  Chrome plated  ,  33mm .

BACK  .  Screw  ,  steel .

           Shows , from top to bottom : “stahlboden” , “wasserdicht” , “incabloc” , DU  and the S/N .

           Inside , the brand name is reported .

MOVEMENT  .  AS 1130 , anonym . 

PUNCHING  .  D. U.  only .

                    writing and number are small and uniform (1mm) . D.U marks are quite large (3mm) . 

S/N  :  The number of registered watches (3) does not allow to define a possible range .

            However , all three watches have a 5 digits S/N that begins with   73XXX .