Cobalt drill bits are made from cobalt steel blended with a fairly large percentage of cobalt. The cobalt actually makes the drill bit incredibly hard, with an abrasion quality. Cobalt bits are also superior for their resistance to heat. Cobalt bits are used for production drilling (repeated drilling or professional projects). Cobalt drill bits are specifically designed for drill into hard, abrasive materials. They are ideal when used to drill into stainless steel, titanium and even cast iron. If you are going to repeatedly drill through steel and other metals, you may want to look at cobalt drill bits, which are cobalt all the way through, can be sharpen when needed. Precision offers sizes even from 0.1mm steps. Precise to 100% accuracy. Weight(KG): 0.100