They work perfect for forming crown edges and reducing crown boarders to correct size before porcelain firing. Also, the discs work well for constructing and shaping acrylic and ceramic surfaces.  For infinitely variable comparison of boundary positions from metal to blending. It’s a great finisher of interdental area with bridges. The ideal RPM is 8,000-10,000 and is not to be used as a separating disc. Available in Coarse, Medium, Fine, X-Fine and an assortment pack plus one mandrel.