I'm looking for some sort of spec sheet Zhangliqun , What is the Tolerance of the A9? what is magnetic performance specs? i know there is several variations . Also what do you use for Surface finish
I don't make the magnets, I just buy them. As for tolerance, I don't know what spec you're looking for on that -- Oerstads? Coercivity? Gauss? Composition? Length/width/thickness? Keep in mind that even in the same batch, they won't all be exactly alike.
All the A9's I've seen come with a strange rough, almost corrugated finish.