Soft Red Gummi Stone. For fine buffing and polishing on the edge. 40 x 20 x 65 mm. Starting at the tip of the ski / board, the gummi stone should be run at a 45 degree angle for up to 10 to 20 cm past the contact point. Making multiple passes, reducing the length of the stroke each time, feather the edge from the tip to the set bevels. Run the gummi stone from tip to tail to deburr and repeat the detune process in the tail.