ATOMA Diamond 1/4 size Convex Whetstone #400, Rough Grit (medium range)
Size: 4 1/2 inch X 1 1/2inch X 1 3/4 inch (115mmX35mmX45mm)
It is not flat surface. It is slightly rounded convex surface.
It might be great sharpening stone to sharpen hollow ground shaped surface or sickle shaped blade.
It is 1/4 size ATOMA rough grit (medium range) stone.
It might confuse #400 and medium range, but ATOMA has #140, #400, #600, and #1200, so #400 is the second range from the lowest grit (#140).
ATOMA #400 Diamond stone is still pretty agressive sharpening power.
It is small size, so it is great to carry outside work for sanding and sharpening.
****After used the Atoma Diamond whetstone, we should rinse slurry well, and dry it. It prevents the rust of the Atoma Diamond whetstone*****