I would say a nice example 1955 American Clipper
I'm very tentative on this being a 1955 American Clipper. It seems to me that the advert is too far off to the date of this watch, being from 1958-9. We have a similar watch in the dB identified as Unknown.
I rather think this is also an Unknown model
Nice example of the American Clipper.
PJ, can you confirm that the outside back case has a date stamp of L5. I think it's just below the BULOVA QUALITY stamp.
There is also an advert from December 1956 advertising a watch very similar as the 'American Clipper". Difference is the dial X shading on the subject watch. I'd be tentative Bulova American Clipper.