The hammer core bit has an one-piece design with removable centering tip and allows for 30X faster drilling process. Use the hammer core bit for extremely hard to crush materials or reinforced concrete as the multi-tooth design allows for aggressive, fast, clean cuts. When using hammer core bits, pull the center bit out after drilling in about 1/4". This will save wear on both the center bit and the hammer core bit. Includes drift key and 7/16" center bit.