1、The tube expander drill bit set can be used to preserve the ductility of copper or aluminum during die forging to avoid cracks and leakage. 2、The set contains 6 expanders of different sizes, which can meet the needs of daily maintenance. 3、The set is used to expand the copper pipe to make the two copper pipes interconnected when the air conditioner is installed. 4、With excellent workmanship, these drill bits are easy to install and has long service life. 5、The forging stopper will provide a large swaging depth to achieve a perfect fit. 6、With professional design and reasonable structure, the set is easy to use and operate and has good performance. 7、High quality material can make sure the durability and stability of the product.