Chef"s Choice 463 pronto manual asian/santoku sharpener is the fastest manual sharpener on the market. The 463 includes two stages, one for sharpening and a second for honing/polishing for a razor-sharp, arch- shaped edge that is strong and durable. 100-Percent diamond abrasives are used in both stages 1 and 2, and the diamond abrasive wheels will hold its shape indefinitely, (unlike ceramic wheels which lose shape over time). The criss-cross sharpening technology creates an extremely sharp edge with lots of bite the diamond abrasive wheels sharpen simultaneously into and out-of edge for a superior burr-free edge. Micron size diamond abrasives in stage 2 leave your knife with a super sharp polished edge. The precise bevel angle control sharpens to an ultra sharp asian-style 15-degree edge. The pronto is safe to use on straight edge and serrated santoku, and other double bevel asian style knives.