CASE : Chrome plated, 33 mm .
BACK : Screw, steel.
S/N and the symbol of Helma ( helmet ) .
MOVEMENT : AS 1130 no name .
CASEBACK MARKINGS: D. H. only .
letters and numbers have the same size ( 1 mm ) .
S/N : 6 digits . Because the small number of watches recorded ( 6 ) it is not possible to define a range .
However , the observed watches had a S/N ranging from 006XXX to 155XXX ,
The numbering is typical of Helma .
1. EDO was produced in Germany by Ernest DOhrman
Probably, the use of Helma cases and AS 1130 move to belive that EDO was an assembler only .
2. S/Ns are purely indicative .