Naniwa manufactures the most advanced easy to use sharpening stones for industrial and home use. Multi stones are the bonding of two traditional stones. Two grits in one stone gives the user better choice for sharpening and finish. Made of a high grade traditional bonded whetstones. 1000 is a fine grit stone that will repair and smooth the edge. 3000 is an extra fine grit stone for finishing a blade or can be used before a finer grit.