[JimH]

Another noob question, a forum search (surprisingly) turned up nothing. I think I'm searching wrong...

What is an "unbreakable mainspring"?
What is a "lifetime mainspring"?

I have seen this printed on the dial of some old watches. I am pretty sure I saw them on regular manual wind watches, so the wikipedia entry which says that this is an "automatic watch" feature doesn't make sense to me.

Thanks!

These are basically the same thing and describe a new type of white alloy mainspring (new at the time) that was much more resistant to breaking or "setting" (assuming the shape of the barrel) than the blue steel mainsprings that were previously in use. Watches with this sort of descriptive language usually date to the late 40s & 50s. The white-alloy mainsprings are used in both automatic watches and manual-wind watches. This is not a feature restricted to only automatic watches.