Our coarser grade diamond abrasive is perfect for hard materials such as carbides, cobalt, tungsten, chilled iron, semi and precious stones. Use wet or dry. Carbide tools: sharpen router bits, forstner bits, shaper cutters and various other tools and remove chips. The sharper-than-factory finish reduces heat build-up during tool operation. Lapidary and watch crystal: ideal for cutting and shaping stones as well as smoothing out chips. Also removes heavy to fine scratches on watch crystals. Recommended use with NINJA cushion item number N-3103. Disc size: 3" diameter. Grit 200.