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 the competition. Ideal for drilling large and small-diameter holes in steel and plastic, these bits are optimized for cordless drills in high speed. The Rapid Strike tip allows for fast, accurate starts that generate less heat, resulting in longer bit tip life. Black oxide coating 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 #4 step drill bit has 12 hole sizes in 1/16 in. increments ranging from 3/16 in. to 7/8 in.. jam-free performance in high speed with most professional 18 Volt cordless drills with lithium-ion battery technology.