Lenox 30884-VB4 Vari-Bit 3/16-Inch to 1/2-Inch Step Drill Bit with 1/4-Inch Shank
The LENOX  30884-VB4 Vari-Bit Step Drill Bit -  3/16" - 1/2"  has a patented two flute design which cuts fast, clean, round holes that are accurate and burr-free.  The enhanced flute design also removes chips rapidly to ensure longer tool life.  The split point on the tip of the Vari-Bit is designed for faster penetration and prevents walking.  The steam oxide coating adds to the durability of the Vari-Bit Step Drill Bit.