It is used for drilling granite and any other durable and hard material. The drill bit is equipped with cutting teeth with diamond chips on its edge, which has basic functions. There is a centering drill bit inside the workpiece, so that the trajectory of the workpiece cannot be changed during drilling. The drill bit is fixed on the drive shaft There are holes in the crown barrel, which is conducive to the cooling of the drill bit, so as to prolong the service life of the whole product.