Accompanied by Uhrenmuseum Glashütte Certificate and a copy of the delivery report confirming the sale of the present watch to the Ministry of Aviation in Berlin and Commander of the Air Force on 27 February 1939 for the amount of 323 Marks. It was part of a series of 25 "Gradmass" wristwatches, numbers 82'544 - 82'569, all delivered on 27 February 1939. As stated on the delivery report, the watches were fitted with the improved version of the calibre 45 movement and, following the regulations of the Commander of the Air Force, with black dials, luminous numerals, luminous hands, lugs and leather straps.
The present watch is fitted with a "Gradmass" dial graduated for 60 and 360 degrees. The second hand makes a complete revolution in 4 minutes while the minute hand progresses of 1 degree (equal to 240 seconds). The minute hand takes four hours to revolve while the hour hand moves forward of 60 degrees, performing a complete revolution in 24 hours for 360 degrees, equal to the rotation of the earth.
These watches were worn by pilots and navigators on the thigh. Consequently the dial layout is made with the "0" (or 12 o'clock) position to 3 o'clock and large luminous indexes and hands allowing reading it also in the dark.
The model is described and illustrated in A. Lange & Söhne - eine Uhrmacher-Dynastie aus Dresden by Reinhard Meis, pp. 296-297.