Large Step Drill Bit - The step drill bit is constructed in 12 step drill bit diameter: 6-60mm (6mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50 mm, 55mm, 60mm). Unique enlarger holes, no need to replace the drill bit and positioning hole during use. Material - The stepped cone cutter made of HSS 4241 high speed steel and titanium coating on the surface. Anti-rust, anti-wear and heat, longer service life. Spiral Design - 135 slotted tip and 2 flute double edge design ensure faster and smoother cutting, stable removal and better chip removal. Three-sided shank fits securely into power tool chuck and prevents slipping. Surface depth gauges make drilling precise. Cool with water - For parts whose hardness is less than 25; For materials such as metal, wood, aluminum alloys, plastic plates, insulation plates, etc. What you get - 1 twist drill bit. Drill speed 250-400 rpm recommended. Note: The data are all manual measurement, please allow 1-3cm error; due to the difference in light and display, there would be some color difference, please refer to the real item received.