That's the men's version indeed, officially 31.5 mm. I happened to be looking at the German 1988 Omega catalogues earlier today where it is featured :
http://www.old-omegas.com/sea88de.html
The 1670/1675 quartz chronos were a larger 37.5mm
The Polaris XL models (German market only I believe) were 39mm (Auto 1120, Ana Digi Cal 1665) and the Chrono might have been 41mm.
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