Two hardened high carbon stainless steel wheels, set so they intersect. Pull a straight edge blade between them once or twice with light pressure and both sides of the edge are sharpened at the same time. That is the whole mechanism, and it is why it takes seconds rather than the patience a whetstone demands.

It is 3½ inches long and 2 inches high, which means it lives in a drawer instead of taking up counter. The base is nylon and wide enough to stay put while you pull, and left handed cooks simply turn the whole thing 180 degrees. Wipe the blade with a soft towel afterward to clear the metal shavings.

Use it on straight edge blades only. Rada does not recommend it for serrated knives, which it builds so that they should not need sharpening. The sharpener is sold on its own; the knife in the photographs is there to show the motion. Made in Waverly, Iowa, with 100 percent American materials and construction, by a company that has been building knives since 1948. Rada guarantees the base, the wheels and the assembly for life.