This is a silicon carbide stone that is perfect for removing lots of material fast. It is ideal for re-doing the bevel on the edge of your knife, or reparing large dents/chipping. It will not give you a razor sharp edge on your knife. Sharpening is a 3 stage process: 1) Bevel the edge. 2) Sharpen. 3) Hone. This stone is only for stage 1.

Functionality: 5/5
+The size of this stone makes it easy to work with large knives

+Seems to wear very slowly

-Better described as coarse/medium rather than medium/fine. The coarse side is not very useful for kitchen knives

Fit and Finnish: 4/5
-Some edges portrude. Using the stone without flattening these can damage your knife

+Stone surface is rather flat out of box, so it does not take much time to prepare

Value: 5/5
+great price

+better quality than other stones I've seen on hardware store shelves

If you're looking for a stone that can quickly profile your knives, this is a great choice. Granted, not as fast as diamond, but far cheaper.