460 x 2,20 x 16,0 x 0,20 mm
Junghans mentions spring number
1007 450 x 2,25 x 0,205 mm
F.W.S 1947 page 74
49 x 66 mm
Junghans catalog 1923 text:
7 jewels, Breguet compensating hair spring, lever escapement with visible jewels, double safety roller, gilt plates, exactly regulated.
These watches can also be supplied with Radium luminous (RZ)
Here are some hints how to separate some Junghans movements from themselfs.
Is it a J26 or a J31/J32?
As you can find J26, J31 and J32 movements without markings and as they look the same, there is this little hint, which can help you to determine if you have a J26 in hand or a J31/J32, without taking the watch apart.
Use a caliper and messuare carefully the distance between the top of the top plate and the top of the bottom plate. If more than 4 mm it is a J26.
Another feature which distinguishes the J26 from a J31 and a J31 from a J32 are the amount of screws on the balance wheel.
J26 14 screws, J31 8 screws and the J32 has 16 screws.