Material: HSS4241, high hardness, anti-rust, strong and durableSplit Point Tip: Increases cutting speed with self-centering and prevents walkingDesign spiral: 2-flute spiral blade design makes cutting faster and smoother, and automatically deburrs from the hole when the bit is drilledApplication: Suitable for cutting holes in a variety of materials like iron plate, aluminum plate, insulation board, PVC sheet, etc.Package includes: 1 x 6-60mm HSS Step Drill Bit (12 Steps : 6mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm) each step is 5mm in height, which perfectly meets your your different drilling needs. Step structure: Unique ladder structure, it can open multiple openings. Note: 1. The recommended drilling speed is 250 to 400 rpm. 2. Sometimes please add a little water or coolant to prevent the material from smoking when using.