From the Junghans catalog from 1934:
"Junghans "Master" Watch, thin model, hunting case, Savonnette, bridge movement. 15 jewels, cut compensation balance, Breguet steel hair spring, regulating spring, lever escapement with visible jewels, steel escape wheel plain polished double safety roller,
gilt plates and bridges. Adjusted in different temperatures, hanging and lying, down to a few seconds."
1928 - 1937
J42, J42a, J42/1, J43 for Alpina
F.W.S 1942 page 18
52 x 68 mm