MaterialMade of high speed steel (HSS), high hardness and rust resistance for long service life. 6 Sizes Set: M3(0.5mm), M4(0.7mm), M5(0.8mm), M6(1.0mm), M8(1.25mm), M10(1.5mm). 6pcs steel drill bits, perfectly meet your different needs. Sharp and hardened wear-resistant drill bit induction slightly induced to ensure drilling speed and improve work efficiency. High EfficiencyDrilling, tapping, deburring and countersinking in one operation saves processing steps and time costs, improves work efficiency. ApplicationSuitable for drilling wood, plastic, thin copper, aluminum and other soft metals (5-6mm), not for hard materials (e.g. steel sheet). PrecautionsWhen drilling a hole, you must inject water at the same time to cool the drill. If you cannot cool the drill when drilling holes, the drilling speed should not be too fast and you should not drill too frequently.