Every skier or snowboarder should own a gummi stone. The Wintersteiger Gray Gummi Stone is great for removing rust and burrs from skis and snowboard edges. This gummy stone also works as a fine polishing tool on your edges, after edge grinding and filing is complete. The Wintersteiger Gray Gummi Stone works well for feathering back or detuning the tips and tails of skis. Some ski tuners refer to this as an eraser stone