High-Speed Steel Step Drill Bit Sets Multiple Hole Step Drill Bits for Woodworking 3Pcs High-speed steel along with the strong coating ensures extreme durability, will stay new and it can shiny for years to come. High-speed steel step Drill Bit Set provides fast and smooth drills on steel sheets, aluminum sheets, wood board, plastic board etc. (the board must be smaller in thickness than the height of step drill bits) Before use please mark the spot that you are to drill for easier drilling and improved drill bits life. Material: high-speed steel Capable of cutting holes from 4 mm to 32 mm through three different step drill bits What’s in the box 1 x Five-Step Bit (4-12mm) 1 x Fifteen Step Bit (4-32 mm) 1 x Nine-Step Bit (4-20mm)