So what's the difference between the 904L steel and Surgical SS, guys?

[haakon59]

Rolex is the only wristwatch manufacturer that I know of who uses 904L steel while everyone else uses 316L.

In certain corrosion environments 904L grade steel will have less pitting than 316L, but I would tend to think that most "divers" or people wearing the watch on a normal basis would not encounter this risk. I haven't read 904L handles sea water corrosion any better than 316L, but I do know that 904L performs better with chlorides, sulfer dioxide gas and some other toxic materials. The two are pretty much the same hardness.

904L is more expensive than 316L and has a higher nickel content.

So I am not quite sure why Rolex uses 904L instead of 316L as all the other manufacturers do. I don't think I have ever heard an actual Rolex Representative explain their reasons. But whatever their reason is, they must be convinced they are right because they pay more for it.