Diamond Stones 100mm for racing. White FineFine 600 grit. First diamond stone when you have smooth, clean edge to start honing and polishing the set edge. Great grit for finishing tech skis. Yellow Medium Medium 400 grit. 2nd in your must have diamonds to maintain a smooth and sharp edge. Starts to bring out that high polish shine. Red Coarse Coarse 200 grit. Deburring and maintenance stone. One of two stones that can do it all in the diamond category. Works great for maintaining sharpness and smoothness.