The ultimate sharpening stones! 100% diamond abrasives permanently bonded to an ultra-flat steel plate. Ideal grit size for single-stone sharpening. Sharpens any material: stainless steel and much more. Excellent for a wide variety of knives and tools! Precision-built solid hardwood box with cover protects stone when not in use. Rubber feet secure stone to work surface. 2" x 4", 2" x 6", 2" x 8". Made in the U.S.A.