This is set of step drills made of high speed steel 4241/6542, different specifications can meet different drilling requirements. Widely Used To Cut Holes In A Variety Of Material Like Steel, Wood, Thin Iron, Aluminum Alloy, Insulation Boards, PVC Sheet, etc. Features: Easy to install, suitable for most of electric drill. Constructed of industrial high speed steel with titanium nitride coating for durability and strength to punch and drill clean holes in materials like plastic, aluminum, wood, copper, stainless steel and other types of sheet metal. Two-flute spiral grooved design deburrs chip, dust and debris for clearance and smooth cutting. Quick change hex shank makes for easy, convenient bit switches and is compatible with impact ready power tools. Assortment comes with 3 drill bits of a combined 33 sizes to add to your drilling arsenal: 4-32mm(4,6,8,10,12,14,16,18,20,22,24,26,28,30,32mm), 4-20mm(4,6,8,10,12,14,16,18,20mm), 4-12mm(4,5,6,7,8,9,10,11,12mm). Specifications: Material: High Speed Steel Color: Golden High Speed Steel 4241: Suitable for use in hardness 25 degree below the workpiece High Speed Steel 6542: Suitable for use in hardness 28 degree below the workpiece Surface Treatment: Titanium Coated Structure: Step Core Drill Bits Suitable for use: Thin iron plate, aluminum, insulation panels, PVC panels 5mm thickness within the timber Quantity: 3pcs 4-32mm (4,6,8,10,12,14,16,18,20,22,24,26,28,30,32mm) 4-20mm (4,6,8,10,12,14,16,18,20mm) 4-12mm (4,5,6,7,8,9,10,11,12mm) 4-32mm drill size: 10.22*3.15*3.15cm 4-20mm drill size:7.16*1.93*1.93cm 4-12mm drill size: 7.35*1.16*1.16cm Product weight: 215g Package size: 11.3*4.8*2.8cm/4.44*1.88*1.10in Package weight: 217g Note: Item color may show sight aberration due to different shooting light and monitor display. Packing list: 1* 4-32mm drill 1* 4-20mm drill 1* 4-12mm drill