I have already wore out a DMT8C that I have had less than 2 months. Granted I tried to lap a couple Les Lats with it but even after I stopped using it for them it got progressively duller with each lapping session on coticules, and Naniwas like the 12K stick to it fiercely. Sandpaper is a better value than a DMT for lapping Coticules and Naniwas.