These drill bits are designed for use with a 1/4" hex shank drill and are coated with titanium, providing added durability and resistance to wear. The set includes 13 sizes: 1.5, 2, 2.5, 3, 3.2, 3.5, 4, 4.5, 4.8, 5.0, 5.5, 6, and 6.5mm, providing a range of options for different drilling tasks. The titanium coating ensures that these bits will last longer than regular steel bits, making them an excellent choice for heavy-duty tasks. Whether you are a professional contractor or a DIY enthusiast, these drill bits are an excellent choice for all your drilling needs. With their high-quality construction and precise design, these bits are sure to provide reliable performance for all your drilling tasks.