1931 - 1953
J49, J49G, J49/1
F.W.S 1942 page 18
52 x 68 mm
Junghans catalog 1931 text:
Bridge movement for hunting cases, thin model, 15 jewels, flat hair spring, lever escapement with visible jewels, double safety roller, gilt plates and bridges
G indicates a new click spring assembly from 1934.The suffix /1 means that a seperate escapement wheel bridge/cock is used.
I assume that these watches are made from 1938 or later.