DMT Diamond Wave Extra Fine Convex/Concave Sharpener. This Knife blade Sharpener from DMT is the first to combine a convex and concave diamond surface in one for easier sharpening strokes over traditional slip stones. The juxtaposing pair of 1" to 1/16" tapered surfaces produce radii to accommodate a full set of curved edges. For a great way to make sure your knife is will outperform the rest choose the DMT Diamond Wave Knife Sharpener . Package Contents: DMT Diamond Wave Sharpener DMT DMWAV-E: Diamond Wave Extra Fine Convex/Concave Sharpener