Professional Kit: There are 20 different shapes and sizes of rotary cutters, you can choose different types of cutter heads according to work needs, they will satisfy your different craft creation needs. . Multi-function: Diamond drill bits have 10 different grinding bits for abrasion, carving, cutting, polishing and engraving. . Compatibility: 1/8'' (3.1mm) shank, 39mm length, fit for dremel electric rotary tool and most mini grinder. User-friendly design and easy insertion process, incredibly easy to use. . Quality Material: The countersink bits is made of quality high speed steel with long life, has the advantages of high hardness, good wear resistance and heat resistance. . Our Guarantee: We have confidence in our products. If you have any questions about the product, please feel free to contact us, we will give you a satisfactory answer within 24 hours. .