Cobalt twist drills are more durable than high speed steel drills and are composed of a steel alloy with a higher concentration of cobalt compared to other steels.

While the cobalt drill will considerably outlast its HSS counterpart, it is also more brittle, because it is harder. This hardness and durability make the cobalt drill ideal for working stainless steel, platinum, and most other ferrous and non-ferrous metals. This type of drill also has an advantage over other high strength drills, which achieve their hardness from a surface coating, while the hardness of the cobalt drill is uniform throughout the tool. A cobalt drill can be sharpened repeatedly while retaining its high strength. Available in diameters from 0.5 mm to 2.3 mm. 3/32" shanks.