The sunnen web site does not do a whole lot to help choose stones. Sunnen could do a lot better job at selling their product with video and such which I have suggested to them.
There are a lot of factors that go into which honing stone to choose. If you call Sunnen and talk to them the technicians are very helpful and knowledgeable.
basically you need to figure out what surface finish you want, how much material to remove, and how hard the metal is that you are honing.
Even once you know all of those things there is still some trial and error.
I did a lot of honing at my last job and had to learn a lot about the process. Even after honing for a couple of years and standing in front of our MBB1660 for hundreds of hours I was still ordering different stones and trying new things to shave off time. Towards the end of my time there I ordered some stones that caused me to cut the honing time on bare aluminum in half! So the "right" stones make a big damn difference. Lots of learning.......
Oh and the oil makes a big difference too. I was using the honing oil that Mcmaster sells for a while just cuz it was cheap and easy. Changed over to Sunnen oil and it was a major upgrade and really was about the same price, maybe even cheaper.
You might think that I am getting a kickback from Sunnen after reading this, but I am really impressed on how good they are at this process. Then again, having five or so years experience with honing is not shit. I'm sure there are other companies doing this stuff that I don't know about??