3-In-1 master set includes Fractional, number, and letter sizes. Includes BONUS Center Drill! High production grade M42 Cobalt Jobbers Length drills are made with 8% cobalt and are ground from a solid blank. This type of drill is used in high tensile material such as stainless and titanium. Ground from M-42 cobalt Solid Blank. 135 degree split point. Jobber (standard) Length General Purpose. Number Drills #1 through #60 (0.228″-0.040″) wire gauge drills. 1/16″ to 1/2″ by 64Ths. Letter Drills A through Z. Sturdy Huot USA drill index.