DICKORON DUO sharpening steel is a combined sharpening steel from two materials - the diamond surface is intended for precise sharpening and ceramic surface for final blade polishing. Dickoron Duo sharpening steel is a perfect combination of both materials: Two polishing flat bars with a diamond surface are set in the flat ceramic sharpening stone. Millions of diamond particles sharpen your knife precisely, but gently. The ceramic surface with its grain size of 1,000 (the equivalent of 3,000 according to the Japanese standard) polishes your knife very gently. Both surfaces - diamond and ceramic one - are extremely hard and therefore are suitable mainly for hard steel knives.