Extra hard Tsushima Nagura !
Very good stone as Aoto specially for Razors and Tools but can also be used for knives.
Tsushima Naguras is very clean stones, so no inclusions or lines you have to worry about.
Also stone comes lacquered on all sides and button and ready to use :)
Approx. grit is 5 k -8k
Approx. Size: 210mm 75mm 50mm
They are very similar stones so picture is just example of the stone.
All prices are in USD