This is a kind of quality core drill bit, with fast cutting speed, and the holes are round, neat and free of burrs. The cutterblade is sharping, large opening with small resistance, which is fine for chip removal. 22 kinds of specifications available, you can choose 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 32mm, 35mm, 38mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 68mm according to your demands. You can have a try. Features: Made of quality diamond material, wear resistance and can provide long service time. Brazed with diamond, it can be used to drilling directly without adding water. Equipped with clearly laser marking, size will be saw at a glance. Fast cutting speed, the holes are round, neat and free of burrs. The cutterblade is sharping and firm, and it is difficult to wear. Large opening with small resistance, which is fine for chip removal. 22 kinds of specifications available, you can choose 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm,