[Rusty]

On October 15, 1940 Hamilton introduced the 992B, also an Elinvar hairspring. All watches were fitted with that spring which was 36% nickel steel.

Source: Collecting Watches by Shugart and Hanson

 

[mgiraz]

Those of us who own Seiko Monsters also have hairsprings made from this rustless alloy. Even early Rolex's used Elinvar!

 

[Rusty]

Interesting. . . I did not know that. Thanks, Dodger blue.