Step Drill Bit High Speed Steel Hole Cutter Tool with Hex Handle for Drilling Wood4mm~12mm Item Type: Step Drill Bit Material: High speed steel Uses: Drilling wood, stainless steel, plastic plates, copper plates, aluminum plates Applicable Equipment: Electric drill, bench drill, battery drill, etc. Shank Type: General hex handle Size(Approx. ) Step number Blade length per step(Approx. ) Shank diameter(Approx. ) Total length of cutter head(Approx. ) 4 ~ 12mm / 0.2 ~ 0.5in  5 7mm / 0.3in 6.35mm / 0.3in 43mm / 1.7in 4 ~ 20mm / 0.2 ~ 0.8in  9 4.5mm / 0.2in 6.35mm / 0.3in 55mm / 2.2in 4 ~ 22mm / 0.2 ~ 0.9in  10 4mm / 0.2in 6.35mm / 0.3in 55mm / 2.2in 4 ~ 32mm / 0.2 ~ 1.3in  15 4mm / 0.2in 6.35mm / 0.3in 78mm / 3.1in