50 sizes in total across multiple step ranges: - 10 steps: 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4", 1-3/8". - 12 steps: 3/16", 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/16", 5/16", 5/16", 7/16", 1/2", 8 inch 8 /16", 3/4", 13/16", 7/8". - 9 steps: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4". - 13 steps: 1/8", 5/32", 3/16", 7/32", 1/4". 9/32", 5/16", 11/32", 3/8", 13/32", 7/16", 15/32", 1/2". - 9/32", 5/16", 11/32", 3/8", 13/32", 7/16", 15/32", 1/2". - 6 steps: 3/16", 1/4", 5/16", 3/8", 7/16", 1/2". A variety of drill sizes are perfect for your needs and save time. High Quality Material: These step drill bits are made of heat treated 4241 high speed steel HSS with titanium nitride coating. Titanium coating reduces friction and runs cooler, helping extend service life. Ladder Structure: One drill can drill holes with different specifications without having to buy multiple drills, saving space and money. Special Design: Provides faster, smoother cutting and a tri-flat shank ensures a firm grip. Triangular round shank can be easily inserted into a power screwdriver, drill and press drill.