Irwin 1877240 Speedbor Max Speed Bit Set, Tri-Flute, 5 PiecesHighlights: Series: MAX Speed Type: Clam Number Of Pieces: 5 Specifications: 4" Hex Shank, Screw Tip Suitable for Use With: 1 4" Quick Change Chucks Includes: 1 2", 5 8", 3 4", 7 8" and 1" Drill Bit Size Range: 1 2" 1" The fastest Speedbor ever Tri flute design for faster chip ejection Cutting spurs have 3 cutting edges for added durability Full screw tip allows bit to self feed Grooved hex shank prevents slipping in drill chuck or bit extension