Premium grains coating, , well-balanced, , aggressive. 20 Pcs 60-grit coated grinding bits, 3mm shank compatible with for 1/8Inch(3.175mm)collect, 10 types of head shapes, head dia 6.2mm, total length 45mm Work great for a variety of uses, grinding engraving trimming porting polishing carving deburring cutting drilling sculpting milling sanding elongating enlarging stone stained glass headstone glass porcelain ceramic metal steel glaze wood quartz moonstone crystal riverstone flagstone soft apatite mosaic resin hard rock jewelery jade marble . These grinding burr bits can remove pits of auto rust to bare metal, grinding broken screws, grinding pet's hard nail. Please use water to cool the bits., Manufacturer: Akfldms