are a different way of sharpening knives. They're basically a two-sided block of coarse stone (with one side more coarse than the other) and a base/holder. A whetstone is much harder to use. To get a ...

"They're bad for your knives," I complained. "They grind away too much steel." Yes, that may be true. And if you use one to sharpen a $600 knife, you will lose your cutlery privileges for a period ...