[High-quality materials, quality assurance] Drill holders and cone drills are made of high-quality HSS stainless steel, durable. Operation suggestion: When using the electric drill, it should be as vertical as possible, do not shake or tilt, and the electric drill should not rotate too fast.Saving time and labor work, efficient and fast] The HSS cone 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 slipping, making drilling easier and more efficient.Three sizes to meet your needs4mm-12mm, 4mm-20mm, 4mm-32mm, you can choose different drill bits according to your needs.A wide range of uses] The product can process thin iron plates, aluminum, insulation boards, PVC boards, wood boards and other materials of a thickness not more than 3mm.Nylon cloth bag is convenient to carryThe product is equipped with a nylon cloth bag, which can achieve good storage and protection effect. There is no need to worry about the loss and wear caused by the small product.Specific InformationSize 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: 4,6,8,10,12,14,16,18,20Size 3: length 10cm, diameter (mm) : 4 to 32:Automatic center punch and high blowProvides 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; Aluminum protective case to make the tips not easy to blunt Wide applications Titanium coating ensures easy cutting through most steel sheets, aluminum sheets, copper and plastic boards, wood and many other types of sheets with ease