The Naniwa Nagura Stone is an optional stone for use on finer Naniwa stones. It used to create a slurry on your stone prior to sharpening. 2 3/4" long x 2" wide x 1 3/8" thick.
We've found this Naniwa Dressing stone (Nagura Stone) to be most useful on the Naniwa Professional Series as well as on finer Naniwa Stones (5000 and above).
Made in Japan.