[High-quality materials, quality assurance] drill holders and cone drill bits are made of high-quality HSS stainless steel, durable. Operation suggestion: When using the electric drill, it should be as vertical as possible, not shake or tilt, and the electric drill should not rotate too fast.Time and labor saving, efficient and fast] The HSS taper drill bit is made of high-speed steel, which can reduce heat and friction, cool quickly, and automatically remove debris in the hole when drilling. The spiral design can prevent slippage, making drilling easier and more efficient.Three sizes to meet your needs 4mm-12mm, 4mm-20mm, 4mm-32mm, you can choose different drill bits according to your needs. not exceeding 3mm.Nylon cloth bag is convenient to carryThe product is equipped with a nylon cloth bag, which can achieve a good storage and protection effect. There is no need to worry about the loss and wear and tear caused by the small product. Specific Information Size 1: length 7cm, diameter (mm): 4 to 12: 4,5,6,7,8,9,10,11,12.Size 2: length 7cm, diameter (mm): 4 to 20: 4,6,8,10,12,14,16,18,20 3: length 10cm, diameter (mm): 4 to 32:Automatic center punch and high blow Provides automatic, high-impact, spring-loaded adjustment through the cap; its brass body has a knurled surface for non-slip control; and the tip with carbide tip makes the center punch 10 times stronger than the normal punch; protective aluminum case to make the tips not easy to dull Wide applications Titanium coating ensures easy cutting through most sheet steel, aluminum sheet, copper and plastic board, wood and many other sheet types with ease