The Chosera stones are markedly harder than the Super Stones. Naniwa designed these stones for professionals who put the highest daily demands on their knives. Overall, these stones are best for those who don't have a lot of time to spend and need to quickly and cleanly sharpen their knives. Every Chosera sharpening stone is delivered with a special Nagura stone (67 x 49 x 25 mm) to put a fine sharpening paste on the surface of the Chosera stones during use. This 10k stone is a wonderful final stage for most knives. We recommend using this after the 3000 or finer grits. Naniwa claims these are splash-and-go stones, but users say that soaking for 15 minutes really brings out the best qualities of the sharpening matrix. These stones measure 210mm x 70mm x 25mm.