A. Lange & Söhne. An oversized German military steel manual wind observation wristwatch
Date: Circa 1942
Movement: Jewelled manual wind, No.210116
Dial: Black, luminous Arabic numeral hour markers, luminous outer minute divisions with 5 minute markers, blued steel sword hands with luminous inserts, centre seconds
Case: Polished round, snap on back, band engraved FL23883, No.210116
Signed: Case & movement
Size: 55mm
Footnotes:
In the 1940's, the German Air Force or Luftwaffe, commissioned watches for their pilots from IWC, Laco, Stowa, Wempe, and A. Lange & Sohne.

Produced to the Luftwaffe's specifications, the watches all have a mechanical movement with centre seconds, cases measuring 55mm to accommodate the large movements (which were typically used in pocket watches) and have an oversized crown. The watches would all be fitted on an extra-long leather strap so they could be worn over a flight jacket. The crown could be operated with gloves on pulling it out stops the central seconds. The movement would be surrounded by an iron core, making the watch anti-magnetic.

These watches became known as the B-Uhr style, abbreviated for Beobachtungs-uhren, or 'Observation' watch. The B-Uhr had two dial variations - Type A dials featured a standard outer minute track and large triangle at 12 o'clock, while the later Type B dials had an inner hour track and outer minute track.

The watch cases were engraved on the left side 'FL23883' to identify the watch was for navigation. On the inside of the case back, it contained further identifying numbers and information: type (Bauart), production number (Gerät-Nr.), movement (Werk-Bez.), order number (Anforderz), and manufacturer (Hersteller).