Hole is also known as hole saw or Drill Pipe in stock  hole saws, modern industrial or engineering refers to the processing of a circular hole cutting class Special saws, hole with different pore sizes and specifications according to the circle of different sizes, but also with at different depths of the openings, we divided into standard openings and deep carrier-type hole saw two,drilling crossover subs  it installed in the hand drill, impact drill, radial drill and other power tools, simple and flexible, easy to carry , safe, and versatile.