This is a unique little polishing stone. Named the han han it is a hybrid stone that uses natural stone material ground and then bonded like a synthetic. We have limited quantities of these stones available and they're not making more of them. The curved shape on the top of the stone helps you do concave polishing of tradistional Japanese knives.
This in my op is one of the best "hybrid" stones I have ever used it requires quite a bit of water due to the small size and the knife pushing the water off,it builds swarf easily and my guess is it can be used as a finishing stone grit is somewhere around 8k and capable of higher if light pressure is used,I won’t be caught dead without one. Only complaint is I wish it was bigger and I think I have a solution for that also. Buy two mount on glass and blend them togeather like a shapton gs. Peace jmbullman