These step drill bits are designed to drill out holes and recesses to fit the specialized screws we sell, as well as our kit handle screws. These are not jobber quality tools, these are made to our rigid specifications using American Twist Drills and are very well made and precise. We do not recommend using them on steel or metal, but they are perfect for most other materials, primarily handle making usage and various other specialty precision uses. These are extremely hard to find.