This drill bit set contains 3 size: 4-12mm, 4-20mm and 4-32mm, comes with a portable cloth bag. Two flute design provides faster and smoother drilling, with little pressure and the sets can cut through wood, plastic and other surfaces less than 5mm thick. Step cone drill bit design for precision drilling Different size holes from 4mm up to 32mm in diameter, optimum speed and accuracy. Titanium High Speed Steel Drill Bits and Application: Conventional high speed steel with titanium coating for proven capability and durability in drilling holes in plastic, aluminum, copper and many other types of sheet metal. Titanium drill bit is especially suitable for copper and aluminum parts / mold steel / spring steel / cast iron parts / iron and other metal materials. Quick assembly: 1/4" (6.35mm) HEX SHANK works with most drills or drills with 1/4" chuck. Details Material: HSS steel surface Treatment: titanium coated Type: Step Drill Head Type: Hexagon Shank Quantity: 3pcs Color: gold Sizes 15 Step: 4-32mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm) 9 Step: 4-20mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm) 9 Step Bit: 4-12mm (4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm) Hot tips Gun drill, table drill. While working when water cooling, can effectively extend the life of drill bit. Cut through wood, sheet metal and other surfaces with thickness less than 5mm. Apply in gun drilling, bench drill. Feature Unique step design, one drill bit can be used to open holes of different sizes, which means the equivalent of a drill box High speed steel tools are good for most general applications, offering a combination of hardness and toughness for wear resistance Have mutifunction, a great assistant to use for deburring, chamfering, expanding hole Stable and working without pre-work. Packed in a nylon bag, providing good protection. The package includes: 1x Set (3pcs) Step Drill