They are made of carborundum,for polishing.Special electric grinding polishing sand ring, often used for metal rust removal, wood,polishing.beautiful shape, compact, easy to use.the quality is reliable, adaptable work environment.high quality, increase the grinding machine bit life Color:Brown+sliverMaterial:Metal +sandpaperSize:Diameter of sanding paper :1.1cmDiameter of pole shank:0.3cm Length 3.8cm Head diameter 0.8cmFunction: for polishingUsage: Set in electric mill metal grinding headPackage include100 x Sandpaper circle2 x MandrelsNote: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.