Irwin Tools IRWIN Step Drill Bit Set, General Purpose, 4-Piece (10225)
The IRWIN Unibit High-Speed Steel Step Drill Set features single-flute cutting edges for greater control and more precise drilling. Three-flatted shanks prevent the bits from slipping in the drill while the non-skid self-starting tips eliminate skidding and the need for center punching. Set includes #1, 2, 4, and 21 size step drills.