[ High quality material ] The rotary cutting tool drill bit is made of ball bearing steel, which is practical and . It has high and uniform hardness and wear resistance, as well as high elastic limit, making it a good helper for your work and life. When connecting air conditioning copper pipes, the flexible copper pipe expands through the rotation of the drill bit, allowing the two copper pipes to be leak proof. When used in combination with drill bits and impact drills, it is more effective than round headed hole drilling tools. It is very suitable for HVAC installers to perform air conditioning copper pipe expansion operations without the need for complex learning, making it easier to use. (Please wear burn gloves, goggles, and other safety during operation.) 6 different sizes of drill bits, including 1/4 inch, 3/8 inch, 1/2 inch, 5/8 inch, 3/4 inch, 7/8 inch, and 1/4 inch hexagonal handles. Our expansion tool is an essential accessory for repairing air conditioners. When one is damaged, you can easily replace it to avoid delaying maintenance work without a model of the same size. Compared to other copper pipe expansion tools, our drill bit kit can be carried around or placed in a toolbox without taking up space, making it easier to carry and store. Tip: If you have any questions, please contact us and we provide you with the most professional service!