A2 and A4 stainless steel bolts - surface finish ?

[greybeard]

On this side of the pond, fixing suppliers offer stainless bolts as either A2 or A4 specification.
I know less about metal specifications than the little I know about musical instrument building, but I want to use stainless button head socket screws/bolts on a hammered dulcimer I'm building.
For aesthetic reasons, I want to get the grade that has the "mirror" finish rather than the duller one, but nowhere can I find the info on which is which.
A4 is described generally as "suitable for marine environments, and I suspect this is the dull one.
Could someone confirm this for me, or put me right ?

John

[greybeard]

while waiting for some help, further research suggests that it's a non-question.
A2 and A4 grades do not directly determine surface quality, which is a function of the method used to finish the surface.



John