I thought I'd wear this one today, my avatar watch, one I've had for a number of years -- and show p. 121 of A Journey Through Time where the model is referenced. The case and dial are of very interesting design (the dial is similar to that of the CK 710 AN pictured, almost identical but for the subseconds chapter). The fixed wire lugs make it difficult to find just the right strap. I believe this is a very scarce model, at least state-side -- mine is the only one I've seen.
Very interesting watch . I wonder how many times a watch like this has slipped under the radar and gone unnoticed by most of us.
About 31mm I think (from memory). Not terribly large by even '40s-50s standards. 18mm interlug width.