The Purple Dome Top Fine Grit Disc is a 2" diameter rounded steel disc coated with a heat infused tungsten carbide MCM raised grit. The purple disc was designed to be used after trimming your animal with the 4-Tooth Chain Disc to smooth out the hoof wall and even up the sole. You'll find that the purple disc works similarly to your hand rasp. All of our abrasive discs are designed to eliminate heat buildup on the hoof. If material build-up occurs on the disc, waste is easily removed using a small propane burner, brass metal brush and cleaning solvent.