Irwin Step Drill Bit Set: 17 Hole Sizes, 1/8 in to 3/4 in, 1/4 in Shank Hex Size, Black Oxide Finish

Step drill bit sets contain multiple bits in different sizes for creating holes in a range of sizes. These cone-shaped bits have steps of increasing diameter marked along their cutting head. As each bit is pushed into a piece of sheet metal or other thin material, each step on the bit widens the hole. The bits also have a self-starting split point that prevents the bits from moving, or walking, when starting to drill, which eliminates the need for using a center drill to create a starter hole before drilling.