Milwaukee® Step Drill Bits with JAM-FREE Performance feature a dual-flute design delivering up to 2X faster hole times, up to 4X longer life and up to 50% more holes per battery charge than competitors. Ideal for drilling small and large-diameter holes in steel and plastic, these bits are Optimized for Cordless Drills in High Speed. The Rapid Strike™ tip allows for a fast and accurate start that generates less heat, resulting in longer bit tip life. Black oxidecoating also enhances durability, hole quality and bit life.For user convenience and accuracy, each bit has laser-engraved reference marks you can see while drilling. The 3-flat Secure-Grip™ shank ensures a solid connection with the drill chuck. The Step Drill Bit 4-Piece Set includes bits #1 (48-89-9201), #4 (48-89-9204), #7 (48-89-9207) and #12 (48-89-9212). Jam-Free Performance in high speed with most professional 18 volt cordless drills with lithium-ion battery technology.