HSS Drill Bit High Speed Steel Carbide Tip Hole Saw Drill Bit SetHole Saw Cutter before in use, be sure to grasp reasonable, choice, control, tachometer and continuously added to the cooling fluid, in order to prevent edge cracking, such as high speed gun drill used in the operation should control switch, so opening and closing to minimize its speed, widely used in conjunction with various types of drill hole drilling on the bench. Chip smooth, sharped edge, wear and other advantages. Specifications: Material: hard