norton JB45?

I have a Norton Crystolon Combination oilstone JB45. It is like new in box and belonged to my Grandfather. Does anyone know what the grit level on the two sides are, or anything else about this stone?

The coarse side is around the 120 grit, and the finer side is around the 320 grit. It is a very good stone to create a new bevel on heavily damaged knives, it grinds metal fast, but it'll leave deep scratches. It is a good stone when you want to remove metal fast.
What I meant with "knives' is kitchen knives, you could use it for chisels too.

Thanks. Thought it might be a bit to much for a razor bevel set. I did use it to take out a large chip in an old blade once. It worked great for that, but I don't think I want to use it on razors normally.