Hektor 6.3/2.8cm 'W.haven'

extremely rare Hektor 2.8cm for the German Navy, engraved on rear with 'W.haven'" and Reichsadler (Wilhelmshaven - the naval port of the Kriegsmarine during WWII), a similar lens (no.580140) is illustrated in Lager I page 95, only 30 of these lenses are known to exist, all of them have been delivered on August 23rd, 1943 to Berlin 9839, the offered example is in beautiful, almost mint condition