【DRILL SIZE】 1 × (4-32mm) Spiral Step Drill Bit, The drill sizes are clearly laser engraved, making it easy to drill accurately. Pour water while the step drill is working, can effectively extend the service life. 【TWO-NOZZLE SPIRAL GROOVE DESIGN】 Cutting faster, more stable and smoother. It can automatically chamfer the hole to clean the drill bit. 【TIME SAVING】: Covering different step sizes allows you to drill or enlarge different holes in one drill bit without constantly changing drill bits. The size is laser engraved into the metal, so it can be drilled accurately and will not wear out even if used for a long time. 【APPLICATION】Suitable for sheet metal, sink, auto repair, etc. Widely used for drilling holes in a variety of materials like plate, aluminum, insulation board, PVC board, wood thickness within 5mm. Material：High Speed Steel with Titanium Coating