This is a commercial-sized stone from the Kyoto Air Raid Shelter stock that I bought out many years ago. 
 
I have tested and found that this stone will sharpen a wide variety of hard steels. From razors to kanna blades, and knives of many brands.
 
The tenjo suita stones are versatile, and, being from a shallower stratum, they are easy to use. This one is big and thick enough to support a professional shop for years.