Annic HSS Titanium Step Drill Bit 1/4' to 1-3/8' Inches 1/8' Increments, 10 Steps Made of high speed steel model: 1/4-1 3/8 For drilling holes in thin material such as steel, aluminum, stainless steel, copper and more. 10 sizes : 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, 1, 1-1/8, 1-1/4, 1-3/8-inch 3/8" Shank with 3 flats. Double flute for easy control. Self-starting, no walking and center punch is not required