Age determination of service watches B-watches of the Reichsluftwaffe according to code / marking lid

The legendary B-watches of the Reichsluftwaffe in World War II by Lange&Söhne, Wempe, Laco, Revue Thommen and IWC bore a stamp on the inside of the case back with the information

• Type
• Manufacturer
• Device number
• Serial number
• Request mark

and, if applicable, the name of the company that cased and finally assembled the clock

This was not done before 1940, for this reason B-watches of the above manufacturers without this letter code are just as genuine and authentic, but built before November 1940

The following years of manufacture can be assigned to the letter code next to "Bauart" if this is not possible due to the manufacturer's serial number lists (Laco, Wempe ...):

az and azz October 1941

aaa-azz November 1940

baa - bzz February 1941

caa - czz March 1941

daa - dzz April 1941

eaa - ezz May 1941

faa - fzz June 1941

gaa - gzz July 1941

haa - hzz August 1941

yes - jzz September 1941

kaa - kzz June 1942

laa - lzz September 1943

maa - mzz December 1943

naa - nzz August 1944

oaa - ozz October 1944

Source: Konrad Knirim "Military Timepieces)