Whetstone Cutlery? two-sided whetstone come has two different sides of grain for sharpening and polishing knife edges. The stone is suitable for use with either water or oil.
These softer Japanese stones have several advantages over harder stones. Because they are softer, they do not become glazed or loaded with detritus. Plus, they are lubricated effectively with water rather than oil, but can be used with either.
Features Include:

2 sided rectangle stone block
Side A (darker green): 400grit for rough grinding, to return edges to their original shape.
Side B (lighter green): 1000grit is for fine finishing, smoothing and polishing cutting edges.
In addition, with these stones the worn material and the water form a slurry, which in conjunction with the stone, sharpens and polishes the blade.
Overall dimensions: 7 × 2.25 × 1.125 inches

Instructions:
Submerge the stone in water for about 5 – 10 minutes. Continue to apply water while sharpening. The stone releases small particles during the sharpening process; this powder in combination with water allows the sharpening. Place the stone on a slip-resistant base like a towel. Start by using the coarser grit of the stone.Move the blade back and forth at an angle of 10° – 15° using gentle pressure.Start at the tip of the blade, continue with the middle section, and finish at the end of the blade. After a while you will notice a small burr at the edge. Now repeat the same process on the other side of the blade. Finally, turn the stone over and repeat the procedure, this time using the finer grit of the stone. In order to remove the remaining burr, pull the blade at an angle over the stone. Now you will have achieved the best sharpness. Rinse the stone and clean off the grinding residue. Clean your knife with hot water.