This range of precision credit card stones are 1.6mm thickness means no flexing as in cheaper thinner products and are made with Monocrystaline Diamonds to give the maximum performance possible . The stones range from Extra Coarse / Coarse (180/300 grit) perfect for sharpening roughing gouges, hss hollow inserts/corning inserts, through to the woodcarvers stone which is Fine / Extra Fine (600 / 1000 grit) for precision honing and gaining bthe keenest edge on small carving tools etc. Don't forget to buy your TITMAN EDGE lapping fluid to guarantee a 5 year warranty on the stones.