This product is made of high-speed steel, small drilling resistance, chip removal smoothly. Smooth surface finish, long service life. Suitable for wood, plastic, etc. Great replacement for your dull drill bit to improve work efficiency. Drill Bit Diameter: 2mm/0.08",3mm/0.12",3.5mm/0.14,4mm/0.16",5mm/0.2" Total Length: 150mm/3.94inch Drill Bit Length: 100mm/2.2inch 1 Set x High-Speed Steel Twist Drill Bit Please keep cool and gentle using, the working life of the twist drill bits can be largely prolonged by proper usage.