“HSS CO” and “size”. Engraved on the drill shank. 135 Degree Split Point. High Quality Material – Cobalt Steel providers better performance than high speed steel when cutting harder metal. Gold Coating is used to identify cobalt steel tools. Round Shank fits most drill chucks. Cobalt drill bits are ideal for drilling in harder metal, such as Aluminum Steel, Cast Iron, Stainless Steel, Heavy-duty Abrasive Alloy.