WATCH POP

I read somewhere that Seiko's started to use 316L steel in their Spring Drive models. This sort of baffled me.
I thought they used this particular steel for all their SS models!
My impression is that even lower mid-end segment watch producers in Swiss use 316L steel.

What steel do they actually use in e.g., Grand Seiko line? ...the terrific report produced by Mr Disher. :) here.com/index.php?t=tree&goto=1453245&rid=5