C15k, PHIG, C12k+, People's Hone of Unknown Grit
If the rock is a dog call it a PHUG (sounds like PUG) Peoples Hone Uncertain Grit.
They vary a lot. I own one that was sold as 15K and it is closer to 800 grit. :ziplip:
The rocks from Woodcraft are more predictable than the eBay rocks.
Currently the price is right so give them a try.
Someone is going to find a bluff of superior silt stone on their
back forty and discover that it can be low fired into a very
fine razor hone. The problem is that the market for razor
hones is too small and the bonus is that Japan makes some
top notch ultra fine water hones today.