Material: high speed steel with titanium coating. The drills are smoothed and coated, these drill bits are evenly and sharp, HSS high speed steel and durable. 6 different diameters for choice, metal drill diameter: 1mm 1.5mm 2mm 2.5mm 3mm 3.5mm, each size 10 pcs. Titanium coating Improve the surface hardness of the drill bit, improve the precision of machining, improve the surface quality of the drill bit, reduce the coefficient of friction with workpiece processing, improve wear resistance. Suitable for drilling holes in a variety of surfaces, including including aluminum, wood and plastic, Ideal for DIY, craft project and general building/engineering use. Features: High speed steel, Durable finish. with Titanium which will help them last longer. Pre drilling keeps wood from splitting before putting a screw in it and makes adding hardware go much smoother. Holds stripping screw heads. Normally or bits are stored in cases by size and it would be difficult to find the correct drill bit, this is very easy to choose the correct bit with calipers and we We checked the diameter before using They are very useful in doing some type of DIY, craft project and general Building/Construction Use, it can be used to drill holes in a variety of surfaces, including metal, wood and plastic. Sizes contained: 1mm,1.5mm,2mm,2.5mm,3mm3.5mm < p>Size and quantity: 1.0mm: 10 pieces 1.5mm: 10 pieces 2.0mm: 10 pieces 2.5 mm: 10 pieces 3.0mm: 10 pieces 3.5mm10 pieces Quantity: 1 Set (60 pieces)