Whether it?s for a DIY project or for professional engineering use, the NEIKO 10173A Two-Flute Spiral Grooved Step Drill Bit Set will make easy work out of your punching and drilling needs. Constructed with industrial grade HSS, the Step Drill Bits provide maximum strength when dealing with various sheets or surfaces, such as metal, wood, plastic, aluminum, or copper. Product Features:- Titanium Nitride coating ensures the bit stays cool, reduces friction, and stays durable to last through countless drills.- Quick Change Hex Shank makes it easy for bit switches and is compatible with most impact ready power tools, electric drills, and bench drills- 135° Split Point Tip increases cutting speed with self-centering and prevents walking- Its 2 Flute Spiral Design clears particles while drilling to decrease friction and heat for a cleaner and quicker process- Clear Engraved Sizes for easy identification- 5 pieces and 50 Step Drill Bit Sizes: 1/8? - 1/2? in 1/32? increments (13 step drill)3/16? - 1/2? in 1/16? increments (6 step drill)3/6? - 7/8? in 1/16? increments (12 step drill)1/4? - 3/4" in 1/16? increments (9 step drill)1/4? - 1-3/8? in 1/8? increments (10 step drill)