The kit includes a specially shaped triangular Medium Arkansas Stone
for sharpening serrated edges, a Coarse Synthetic Stone for all other edges and a Fine Arkansas Stone
Smith's and Dan's Whetstone Company are good sources for Arkansas Stones
The most common sharpening mediums are Arkansas stones
(and their manufactured Aluminum Oxide and Carborundum/ silicon carbide counterparts), diamond and ceramic.
Knife sharpeners range from simple rectangular slabs, like the Arkansas stones
many of us grew up with, to more complicated systems that use multiple components, or more high-tech sharpening surfaces, such as diamond and ceramic.
Smith Abrasives got its start in 1886 mining rocks that would become Arkansas stones
, which are acknowledged as the world's best at giving a polished edge to a knife.