Apparently having an unbreakable mainspring was an important feature to advertise in that era, judging from this and other watch ads in that issue.
If you want to geek out on vintage watch ads, check out this issue of Europa Star from 1964. It has a great article on the Bulova Accutron.
That was a nice find of the article on the Bulova Accutron the only vintage that I really like.👍
Semi-retired with a thrifty streak.