The Hammer Core Bit Has An Easy To Use 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 Inch. This Will Save Wear On Both The Center Bit And The Hammer Core Bit. Includes Drift Key And 7/16" Center Bit.