National SemiconductorDiameter 29mm, thicknesses of 6 or 8 mm may fit batteries 386 or 357 accordingly.
Demand button 2 o'clock, Set button 4 o'clock, second time zone at 8 o'clock if applyed.
Regardless of type no. early versions with dot display, lateron with bars
WM-01: 12hr H,M,S
WM-02: 12hr H,M,S,D
WM-03: 24hr H,M,S,D
WM-04: 12hr H,M,S,D
WM-05: 24hr H,M,S,D
WM-06: 12hr H,M,S,MO,D, Second Time Zone
WM-E7: 24hr H,M,S,MO,D, Second Time Zone
WM-09: 12hr H,M,S,MO,D,DOW
Better avoid touching front side of the earlyer versions which consists only of black plastic foil over a thin silicone layer on the chip's bonding wiring.
Very common modules which were mostly equipped by European watch manufacturers.
In general I'd rate reliability and robustness of NS modules as good/average
![Image](http://ledwatch.de/DSCN0076.JPG)