Drilling can be easily started without pre-drilling. Drilling speed is fast and friction is extremely low.It is generally applicable to all kinds of metals, plexiglass and hard plastics.It is very suitable for home DIY and general construction and engineering.Use with needle vice or low-speed electric drill (not applicable to impact drill).Application: High speed steel drill bit set for wood, plastic and aluminum. Ideal for DIY, home and general building/engineering use.Material: high speed steelUses: drilling holes made of aluminum, iron and other materials.16x1.5mm16x2mm15x2.5mm10x3mm10x3.2mm8x3.5mm8x4mm3x4.5mm3x5mm2x5.5mm2x6mm2x6.5mm2x8mm2x10mm*Compare the detail sizes with yours, please allow 1-3cm error, due to manual measurement. Thanks for your understandings.