The HORL ® diamond grinding disc is pre-installed on all HORL ® sharpeners. It enables efficient grinding and delivers excellently sharp results. The industrial diamonds used are suitable for knife steels of any hardness and are considered one of the most durable and efficient abrasives. When used for the first time, some excess diamond particles may flake off, but the standard diamond grinding disc will then achieve the surface it will retain in subsequent use. Used correctly, it should not need replacing.