TEMO M35 Cobalt double flute step drill, 9 size from 1/4 inch (6.4mm) to 3/4 inch (19mm), 3/8 inch (9.5mm) shank M35 cobalt step drill 3/8" (9.52mm) shank 9 hole 1/4" (6.35mm) to 3/4" (19.05mm) 9 hole sizes: 1/4" (6.35mm), 5/16" (7.94mm), 3/8" (9.52mm), 7/16" (11.11mm), 1/2" (12.7mm), 9/16" (14.29mm), 5/8" (15.88mm), 11/16" (17.46mm), 3/4" (19.05mm), with 1/16" (1.59mm) increments. 3/8 Inch Shank with 3 flats to eliminate slipping Smooth cutting double-fluted design for true round hole; Self-starting for clean holes in thin materials The step drill bit is made with M35 cobalt. It is ideal for variety of materials from stainless steel, metal, plastic, fiberglass to wood. They also help to enlarge existing holes. M35 HSSCo is a high speed steel alloy made up of 5% cobalt. M35 is similar to M2, but with 5% cobalt added. The addition of cobalt increases heat resistance. It is widely used in metal manufacturing because of its ability to resist wear over conventional high speed steels, allowing for shorter cycle times in production environments due to higher cutting speeds or from the increase in time between tool changes. M35 is also less prone to chipping when used for interrupted cuts.