The Bosch 35 piece HSS Drill and Screwdriver Bit Set can be used for everyday and heavy duty applications. The special formulated V steel alloy this set can be used with high voltage impact drivers because of their extreme toughness. Torsion control helps withstands the stress of high torque applications. The Drill and Screwdriver Bits have a black oxide finish with diamond ground cutting edges. The centering tip has been designed for precise drilling and good guidance before drilling holes.